essay on the application of genetic engineering in microbiological practice

REVIEW article

Genetically engineered bacterium: principles, practices, and prospects.

• 1 Department of Respiratory and Critical Care Medicine, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, China
• 2 Department of Biomedical Engineering, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, China
• 3 Central Laboratory, Translational Medicine Research Center, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, China

Advances in synthetic biology and the clinical application of bacteriotherapy enable the use of genetically engineered bacteria (GEB) to combat various diseases. GEB act as a small ‘machine factory’ in the intestine or other tissues to continuously produce heterologous proteins or molecular compounds and, thus, diagnose or cure disease or work as an adjuvant reagent for disease treatment by regulating the immune system. Although the achievements of GEBs in the treatment or adjuvant therapy of diseases are promising, the practical implementation of this new therapeutic modality remains a grand challenge, especially at the initial stage. In this review, we introduce the development of GEBs and their advantages in disease management, summarize the latest research advances in microbial genetic techniques, and discuss their administration routes, performance indicators and the limitations of GEBs used as platforms for disease management. We also present several examples of GEB applications in the treatment of cancers and metabolic diseases and further highlight their great potential for clinical application in the near future.

Introduction

Despite the success of modern medical technologies in the prevention and treatment of most human diseases, the rapid increase in antibiotic-resistant microorganisms ( Cassini et al., 2019 ) and chronic patient populations ( Bernell and Howard, 2016 ; Bray et al., 2018 ; Blüher, 2019 ; Khan et al., 2020 ; Powell-Wiley et al., 2021 ), adverse effects caused by chemical drugs, exorbitant medical costs ( Gheorghe et al., 2018 ; Lentz et al., 2019 ), cancers and other incurable diseases urgently require highly economic, convenient and efficient methods for addressing these issues. Increasing evidence demonstrates the links between the dysfunction of the human microbial community and the onset and development of many human diseases ( Gilbert et al., 2016 ; Dang and Marsland, 2019 ), signifying the potential use of microorganisms as an alternative strategy to conquer these issues ( Mazhar et al., 2020 ). Remarkably, bacteria account for over 90% of intestinal microbes, and advances in synthetic biology enable the precise manipulation of bacteria for diverse purposes ( Lawson et al., 2019 ). For instance, technical improvement in Clustered regularly interspaced short palindromic repeats-cas9 (CRISPR-cas9; Li et al., 2020 ; Wang et al., 2020 ) and molecular biological methods (e.g., gene synthesis, DNA/RNA sequence, DNA transfection, clone techniques of large DNA fragment, etc.; Tavanti, 2022 ) greatly contribute to generating various engineered bacteria for producing many proteins and molecular compounds that originate from uncultivated microorganisms, fungi, archaea, microeukaryotes and eukaryotes ( Çelik and Çalık, 2012 ; Gupta and Shukla, 2016 ; Charbonneau et al., 2020 ). Mounting evidence demonstrates that genetically engineered bacteria (GEB) can be orally or intravenously administered in clinical trials to cure different diseases ( Liu et al., 2016 ; Zhang et al., 2018 ). Due to their special colonization ability in solid tumors, intestinal tracts, respiratory tracts, genital tracts, and the oral cavity, GEBs perform their activities by supplying active molecules, interfering with immune cells, restraining pathogenic bacteria, or killing tumor cells by expressing foreign genes or enhancing endogenous gene expression, thus preventing, diagnosing or curing diseases ( Fan et al., 2019 ). Here, we systemically summarize the recent advances in bacteriotherapy, which uses GEBs as the main body, including the introduction of genetically engineered bacteria, engineering techniques, administration strategies, performance indicators, and biological safety. Finally, we describe the preclinical and clinical applications of GEBs and several probiotics in the treatment of cancers and metabolic diseases and discuss their limitations and prospects.

GEB in disease management

A GEB is defined as a bacterium with the ability to efficiently express heterologous proteins or molecular compounds for a specific purpose after genetic engineering. As early as the 19th century, Coley revealed the therapeutic effects of inactivated bacterial mixtures in sarcoma therapy ( Coley, 1893 ). By the end of the 20th century, genetic engineering techniques have been widely used to modify bacteria to obtain the expected compounds. After decades of effort, numerous GEBs have been established for various applications in the food industry, disease treatment, chemical synthesis, environmental protection, etc. Notably, E. coli ( Michael Schultz, 2008 ; He et al., 2017 ; Christofi et al., 2019 ; Terol et al., 2021 ), Lactobacillus ( Yang et al., 2015 ; Lin et al., 2016 ; Chen et al., 2017 ; Oh et al., 2020 ), Salmonella ( Chirullo et al., 2015 ; Zheng and Min, 2016 ; Li et al., 2017 ; Lim et al., 2017 ; Kawaguchi et al., 2018 ) are the most popular bacteria used as chassis tools for constructing different GEBs. In particular, more than 50 bacterial species, such as Bifidobacterium ( Liu et al., 2018 ), Bacillus subtilis ( Westbrook et al., 2016 ), Listeria monocytogenes ( Selvanesan et al., 2022 ), and Lactobacillus brevis CD2 ( He et al., 2017 ; Alfano et al., 2020 ), are being used in health care and scientific research ( Figure 1 ).

Figure 1 . Microbial chassis for GEB construction.

Advantages of GEBs in disease management

To date, GEBs have made great achievements in the management of various diseases, such as infectious diseases, antibiotic-related diarrhea, allergies, and metabolic syndromes, in health care for daily life ( Ma et al., 2017 ; Mazhar et al., 2020 ). Importantly, GEBs have more systematic and comprehensive therapeutic effects than traditional methods in the prevention and treatment of some diseases ( Duan et al., 2015 ; Isabella et al., 2018 ; Kurtz et al., 2019 ) partly because the colonized microorganisms in the body are almost equal to tiny living factories that can autonomously reduplicate, detect abnormal homeostasis, produce therapeutic agents, and initiate self-destruction at a defined time ( Pedrolli et al., 2019 ). Accordingly, GEBs have promising potential to be used at different stages of disease for different purposes. Genetically engineered bacterial vaccines, such as Salmonella , Vibrio cholera , Listeria , and Neisseria meningitidis , are capable of activating in vivo immune protective responses by introducing some effective antigens into low- or nonvirulence bacteria ( Le et al., 2015 ; Herzog, 2016 ; Sharma et al., 2020 ). Using cholera as an example, the oral administration of attenuated Haiti V to rabbits efficiently restrained the colonization of wild vibrio cholera in the small intestine, thus reducing the incidence of Vibrio cholera infection ( Hubbard et al., 2018 ; Satchell, 2018 ). Additionally, genetically engineered Lactobacillus succeeded in detecting Vibrio cholerae in stool samples via the specific phenomenon of “quorum sensing” in pathogenic microorganisms ( Carignan et al., 2016 ; Mao et al., 2018 ). In cancer therapy, some bacteria, such as Salmonella , Clostridium novyi-NT , and E. coli , have a special ability to colonize solid tumors, enabling them to be excellent candidates for drug delivery and drug production ( Wei et al., 2016 ). For example, transforming growth factor alpha- pseudomonas exotoxin-expressing S. typhimurium displayed significant inhibitory effects on the growth of CT26, MC38, and 4 T1 solid tumors ( Lim et al., 2017 ). In melanoma therapy, recombinant S. typhimurium transfected with the interferon-gamma gene plasmid integrated into the N-terminal region (residues 1–160) of a surface immunogenic protein demonstrated obvious toxicity to cancer cells ( Yoon et al., 2017 ). In addition, S. typhimurium loaded with CpG ODN and PD-1-siRNA induced innate immunity and inhibited PD-1 expression, thus killing cancer cells ( Jia et al., 2021 ).

To date, the generally used GEBs are mainly confined to some intestinal diseases, such as inflammatory bowel disease (IBD; Saez-Lara et al., 2015 ) and cholera ( Duan and March, 2010 ; Satchell, 2018 ). For instance, Lactobacillus transfected with interleukin 1 receptor antagonist was capable of reducing CD4 + IL-17A + cells in mesenteric lymph nodes and blocking IL-1-cell signaling, thus alleviating the symptoms of acute colitis ( Namai et al., 2020 ); E. coli Nissle 1917 (EcN) with the expression of cholera autoinducer 1 could restrain the virulence gene expression of Vibrio cholera and, thus, reduce its colonization in the gut ( Duan and March, 2010 ). Essentially, the advantages of GEBs could be briefly summarized as follows: reduced cost of health care because of manufacturing scale-up and long-term effects of GEBs in colonization sites; decreased adverse effects, especially when they are orally administered; and for structurally unstable or environmentally sensitive compounds, free of drug purification and low-temperature storage. Notably, GEBs can produce multiple foreign proteins or compounds in one strain instead of requiring several drugs to achieve synergistic treatments ( Peters et al., 2019 ).

Microbial genetic engineering

Microbial genetic engineering uses genetic operation tools to shear, splice, and integrate the target genes and then introduce them into chassis cells. Thus, the recombinant genes are transferred into the desired products or endow the bacteria with new phenotypes. Due to the great progress in sequencing technologies and bioinformatics, a growing body of functional genes and gene clusters from nonculturable microorganisms are being excavated. How to express functional genes or gene clusters in a chassis cell is becoming a new research hotspot in the study of GEBs.

Indeed, GEB construction mainly includes the following two stages: upstream (functional gene acquisition) and downstream (heterogeneous expression). The acquisition of target genes or large gene clusters is an important part of the upstream stage of constructing an expected GEB ( Cobb and Zhao, 2012 ). Due to the national microbial genome projects launched in multiple countries, numerous potential genes are available to be used for fabricating various GEBs. In fact, the size of the targeted genes determines the choice of MGE for GEB construction. The acquirement and modification of small gene fragments (<10 kb) can be performed using the general or long PCR method or direct DNA synthesis and restriction enzyme digestion ( Fahnøe and Bukh, 2019 ). However, when the gene size exceeds 50 kb, some recombination methods, such as CRISPR–Cas9 and the Red/ET recombination system, are the optimal methods to alter, replace, delete or add bases or gene fragments of plasmids or genomes ( Li and Elledge, 2012 ; Luo et al., 2016 ; Alberti and Corre, 2019 ; Strain-Damerell et al., 2021 ). Specifically, CRISPR–Cas9 can edit bacterial DNA fragments up to 100 kb in a single step in which RNA-guided Cas9 nuclease targets and cleaves DNA fragments, and the final large gene fragments are assembled via Gibson assembly ( Jiang et al., 2015 ).

Cloning target genes or gene clusters into bacterial chassis includes gene transfer and genetic recombination using the techniques of transfection, transduction, conjugative transfer, lysogenic conversion, and protoplast fusion. The DNA size and property of the bacterial chassis determine the transfer methods. Heat-shock and electroporation transfection are widely used to transfer plasmids in E. coli , Salmonella , Bacillus thuringiensis , Pseudomonas aeruginosa , etc. Conjugative transfer and protoplast fusion often involve the transfer of plasmids from donor bacteria to recipient bacteria ( Mukai et al., 2020 ). For instance, the conjugative type IV secretion system is synergistic with DNA-processing machinery termed the “relaxosome,” and a large extracellular tube termed the “pilus” is capable of orchestrating directional conjugated plasmid transfer ( Waksman, 2019 ). Additionally, homologous recombination technologies, mainly including homologous recombination, site-specific recombination, transposable recombination and the CRISPR–Cas9 technique, enable the direct integration of target genes into the host chromosome in an expected strain. The typical homologous recombination methods require more than 1 kb homologous sequences to realize the recombination of target genes into the chromosomal genome ( Beumer et al., 2013 ). Due to CRISPR–Cas9 technology, DNA operation has become much more efficient and accurate, which greatly benefits the extraction and heterologous expression of gene clusters in chassis cells, especially of those with a size of over 50 kb. Transposition ( Martínez-García and de Lorenzo, 2012 ) and homologous recombination ( Wang et al., 2012 ; Davy et al., 2017 ) are also available to integrate exogenous DNA fragments into the bacterial genome. Remarkably, when selection marker or CRISPR editing alleles are not applicable, transposition is an optimal choice for integrating target genes into the bacterial genome ( Jiang et al., 2013 ; Vo et al., 2021 ). To date, the generally used transposases mainly include sleeping beauty, piggyBac ( Tschorn et al., 2020 ), Tol2 ( Ni et al., 2016 ), Tn5 ( Balasubramanian et al., 2021 ; Xu et al., 2021 ), Tn7 ( Kaczmarska et al., 2022 ), and ICEBs1 ( Ni et al., 2016 ; Peters et al., 2019 ; Strecker et al., 2019 ; Wu et al., 2021 ), all of which possess the ability to integrate small or large DNA fragments into bacterial genomes ( Figure 2 ). However, the transposition efficiency slightly decreases as the size of the inserted DNA fragments increases ( Kowalczykowski, 2015 ). Interestingly, several studies have shown that the synthetic Himar1 transposase-dead Cas9 fusion protein, which is characterized by DNA integration ability by Himar1 transposase (a Tn7-like transposon) and targeted localization by programmable dead Cas9, is capable of achieving targeted transposition under cell-free condition, thus avoiding the random insertion of transposons ( Bhatt and Chalmers, 2019 ). This recombination method succeeded in accomplishing the transfer of transposons larger than 7 kb, the accuracy of which was as high as 80% ( Chen and Wang, 2019 ). Similarly, another integrated system originating from Tn6677 transposase utilized a Tn7-like transposon and CRISPR protein to guide RNA-assisted targeted insertion of transposable factors, enabling the accurate insertion of over 10 kb DNA sequences into bacterial genomes ( Nelson et al., 2021 ).

Figure 2 . General used recombination technologies, including phage infection, phasmid transfection, transposition recombination, conjugate transfer, BAC, protoplast fusion, and CRISPR-Cas9 in counter-clockwise order.

However, the plasmid carrying capacity and transposition method do not allow for operating large DNA fragments, especially when their sizes are larger than 100 kb ( Hashimoto et al., 2015 ). To achieve the heterologous expression of large gene clusters, researchers are more inclined to use transformation-associated recombination ( Bilyk et al., 2016 ; Zhang et al., 2019 ), bacterial artificial chromosomes (BAC; Huo et al., 2019 ; Hashimoto et al., 2020b ), phage recombination systems ( Oßwald et al., 2014 ; Nah et al., 2017 ), or integrase-mediated recombination systems ( Du et al., 2015 ; Ke et al., 2021 ; Figure 2 ). For example， the BAC technique enabled the integration of over 181 kb DNA fragments into the genome of Streptomyces lividans TK23 ( Hashimoto et al., 2020a ). Concomitantly, the protoplast fusion method is also an option to acquire new functions for GEBs by integrating two bacterial genomes ( Zhang et al., 2002 ). Although the insertion of foreign genes into the genome is more complex than the plasmid-based expression system, it possesses incomparable stability ( Miyazaki and van der Meer, 2013 ; Pedrolli et al., 2019 ). Collectively, these methods, such as DNA extraction, site-specific mutation, gene insertion, gene deletion, and DNA transfection, have the potential to cater to most genetic manipulations in GEB construction, even when their size exceeds 100 kb. However, it is still a considerable challenge to establish GEBs for reliably and efficiently expressing foreign proteins or compounds mainly because interspecific differences disable the microbial chassis from expressing most foreign genes or gene clusters, even after codon optimization. Therefore, the principal contradiction of establishing GEBs is that gene sequencing reveals an increasing number of functional genes or gene clusters from microorganisms characterized by nonculture, a long growth cycle, or harsh culture, but not enough microbial chassis are available to express or deliver them for disease diagnosis and treatment.

Administration route and performance indicators

Geb administration route.

The route of GEB administration depends on multiple factors, including the target tissues, disease types, properties of heterogeneous proteins or compounds, and chassis cells ( Hosseinidoust et al., 2016 ). However, considering the potential pathogenicity of microorganisms, especially when administered via intravenous administration, the delivery route should be seriously considered at the initial stage of GEB construction in health care and disease management. Intensive clinical trials demonstrate that therapeutic and adverse effects are closely associated with drug delivery models ( Ott et al., 2004 ). To date, the routes of GEB administration mainly included oral administration, intravenous injection, intratumoral injection, nasal administration, and subcutaneous injection.

Oral administration is the most widely used method in bacteriotherapy because of its simple operation, noninvasiveness, and wide applicability. However, the gastrointestinal tract is known to be a complex environment, including drastic pH changes among different organs [pH 1.0–2.5 in the stomach ( Lund et al., 2014 ), pH 7–7.4 in the small intestine, and pH 6–6.7 in the colon ( Kamada et al., 2013 ; Koziolek et al., 2015 )] and differences in oxygen percentages ( Zheng et al., 2015 ), nutrient enrichment, and flora diversity, which greatly affect GEB activity when orally administered ( Sender et al., 2016 ). Notably, the survival rates of GEBs have a great influence on their therapeutic efficacies, but they do not exceed 50% when they are orally taken without extra protection, highlighting the key role of shielding bacteria from a complex gastrointestinal environment ( Heavey et al., 2021 ). Indeed, the emergence of new technologies, such as polysaccharides (alginate, κ-carrageenan, locust bean gum, gellan gum, and xanthan gum; Ta et al., 2021 ), cationic liposomes ( Chowdhuri et al., 2016 ), and mammalian cell membranes ( Cao et al., 2019a ), enable the isolation of bacteria from hostile environments. However, different packaging methods have different effects on the survival rates of GEBs after oral administration ( Chowdhuri et al., 2016 ; Han et al., 2016 ; Sánchez et al., 2017 ; Cao et al., 2019b ; Gharibzahedi and Smith, 2021 ). For instance, liposomal emulsified bacterial vaccines exhibited higher immune-boosting capacity and therapeutic efficiency than the uncoated vaccines in animal experiments ( Naciute et al., 2021 ).

Comparatively, the intravenous administration of live bacteria only occurs in preclinical and clinical cancer therapy due to the high pathogenicity of the systematic administration of GEBs ( Forbes et al., 2018 ). Additionally, nasal drip is another administration route of GEBs. Due to the specific safeguard function of nasal mucosa, intranasal vaccination becomes capable of activating local humoral and cellular immune responses at the entrance of the respiratory mucosa, distal mucosal sites, and their associated lymphoid tissues, thereby exerting prevention or therapeutic effects ( Riese et al., 2014 ; Xu et al., 2021 ). Notably, bacterial administration via blood, nasal or intestinal routes is very beneficial for them to quickly reach disease sites, and thus, in most cases, their therapeutic effects are superior to those of oral administration ( Wells and Mercenier, 2008 ; Pandey et al., 2022 ). However, some studies signified that the oral administration of GEBs was able to produce a higher immune response than intranasal immunization ( Wan and Ping, 2021 ). The controversial issue is probably attributed to the use of distinct disease molds in these studies. In contrast to the treatment of enteric disease through oral administration, intranasal immunization is more suitable for the prevention of systemic allergy and airway inflammation ( Sarate et al., 2019 ). In fact, various recombinant bacteria, such as Streptococcus gordonii, Staphylococci, and Lactobacillus, have shown great potential as active carriers of nasal vaccines ( Mojgani et al., 2020 ; Dadar et al., 2021 ).

Furthermore, intratumoral injection is another key administration route for live GEBs to treat solid tumors. This method is greatly beneficial for reducing the potential systemic toxicity of live GEBs ( Taniguchi et al., 2010 ). The intratumoral injected bacteria actively or passively colonize necrosis because of their homing instincts, chemotactic effects ( Mirkhani et al., 2021 ), and cumulative effects ( Ganai et al., 2011 ). Then, they activate immunogenicity and release toxic molecules to induce cell apoptosis and restrain tumor growth ( Yaghoubi et al., 2020 ; Lin et al., 2021 ). However, this treatment may lead to highly malignant adverse effects because the biological toxicity caused by rapid and massive cell death in highly colonized bacterial tumors is extremely harmful to other normal organs and even induces a cytokine storm, thus leading to patient death ( Karbach et al., 2012 ; Pandey et al., 2022 ). Therefore, the administration route is a key factor in GEB construction for different purposes.

GEB performance indicators

To date, there are still no official standards for evaluating the efficacy of GEBs in disease diagnosis, prevention, or treatment. Increasing evidence has demonstrated that the intrinsic biological property, colonization ability, dose tolerance, and potential pathogenicity of GEBs all influence their activities. Establishing standard performance indicators plays a key role in advancing GEB clinical transition.

Colonization ability

GEB colonization ability refers to their survival and biological inheritance at the expected sites of disease after they enter the body and is an important indicator for evaluating GEB efficacy in disease management. Various techniques, mainly including tissue sectioning, fluorescent labeling, 16S rRNA sequencing, quantitative polymerase chain reaction, etc., have been developed to evaluate GEB conization ability ( Cronin et al., 2012 ; Shen et al., 2015 ). Fluorescently labeled GEBs can be traced and recorded from the initial administration to fecal samples under a fluorescence microscope; sequencing technology could use 16S rRNA gene tags to obtain the current bacterial lineage in fecal samples, thus evaluating the colonization ability of GEBs by comparison with the initial fecal flora ( Shen et al., 2015 ).

Recent studies have identified some bacteria with high intestinal colonization ( Dosoky et al., 2020 ). For instance, E. coli NGF-1 has been found to colonize in vivo for up to 6 months in a stable and persistent state ( Riglar et al., 2017 ). However, various external factors may influence the in vivo colonization ability of GEBs. The key influencing factor is the location of GEBs in the body because each bacterium in our body has a corresponding colonization area in which the microenvironment formed by long-period interactions with other bacteria and mammalian cells provides a safe place for them to proliferate with high genetic stability ( O’Toole and Claesson, 2010 ; Zou et al., 2019 ; Tochitani, 2021 ). Therefore, the disease location in the body determines the species of chassis bacterium, thus enhancing their colonization and reducing the off-target effects of their secreted substances ( Dosoky et al., 2020 ).

Indeed, some studies have taken advantage of organ-specific GEBs to exert their best therapeutic effects ( Tarahomjoo, 2012 ), such as using colon-colonizing strains to treat ulcerative colitis ( Conrad et al., 2014 ) and employing Lactobacillus bacteria, which colonize in the small intestine and colon, to treat Crohn’s disease ( Donaldson et al., 2016 ). More importantly, the administration method also influences GEB colonization ability. The intravenous injected Salmonella typhi exhibited higher tumor colonization ability than the intraperitoneal administered ones. In addition, the tumor size and bacterial number affect GEB colonization in target sites ( Mei et al., 2002 ). Currently, the studies investigating GEB colonization ability, genetic stability, and the mechanisms underlying their activities are still in their infancy, thereby requiring more basic and clinical studies to advance the clinical transition of GEBs.

Dose tolerance

Intensive studies have emphasized the key role of dose in the therapeutic effects of GEBs against diseases ( Ott et al., 2004 ). Bifidobacterium infantis 35,624, which is generally used to treat irritable bowel syndrome, exhibited the best performance at a dose of 10 8  cfu per day, while 10 6  cfu and 10 10  cfu per day did not result in significant differences from the placebo group ( Whorwell et al., 2006 ), thus indicating that the use of bacteria against disease is closely related to the bacterial number. Although a high amount of bacteria generally exhibits enhanced therapeutic effects, potential side effects also increase ( Leventhal et al., 2020 ). The oral administration of SYNB1020 at a concentration of 10 12  cfu per person induced adverse reactions, such as nausea and vomiting, in healthy volunteers and hyperammonemia patients ( Kurtz et al., 2019 ). Some studies further demonstrated that an increasing number of bacteria generally leads to the development of dose-dependent problems and may even restrain immune system memories ( Sivick et al., 2018 ). Therefore, how to achieve better therapeutic effects with low doses of GEBs remains a hot topic in the development of therapeutically engineered bacteria. Increasing their targeting ability is a selective strategy to decrease the administered dose. For example, the expression of tumor-targeting adhesins on the membrane surface of E. coli significantly decreased the intravenous injected bacterial number required for the minimum effective dose ( Piñero-Lambea et al., 2015 ).

Simultaneously, different administration methods also influence the effective doses of GEBs in disease treatment. Lactobacilli were administered via intraperitoneal injection, intestinal administration, and oral administration, but the doses required to reach the same therapeutic efficacy differed by nearly 10,000 times among them ( Steidler et al., 2000 ). Notably, each bacterium has an optimal dose for producing the best therapeutic efficacy. The recommended dose for Bifidobacterium infantis 35,264 is 10 8 CFU per day, while the optimal dose for probiotic preparation VSL#3 (VSL Pharmaceuticals) is 1.8 × 10 12 CFU per day when taken by oral administration ( Gionchetti et al., 2003 ). Although daily probiotic use has a long history, the use of bacteria for the prevention and treatment of disease is still at its initial stage.

Safety evaluation

Using bacteria to improve intestinal function and treat diseases has been proven to be a safe and effective modality ( Sharif et al., 2017 ). However, GEBs prepared by genetic modification, chemical capsulation or other methods need to be fully evaluated for metabolic pathways and toxicological effects in vivo before clinical application. The pathogenicity of GEBs is mostly derived from the bacteria, but this defect could be partly removed or mitigated by the gene knockout or mutation of virulence genes. Typical examples include lipopolysaccharide deletion in gram-negative bacteria, virulence elimination in Listeria monocytogenes , and exotoxin gene knockout in Clostridium novyi ( Zhou et al., 2018 ).

Additionally, the regulation of bacterial population provides another strategy to further enhance the safety of bacteriotherapy. A synchronous lysis circuit consisting of positive and negative feedback genes, and an inducible promoter can precisely control the proliferation and lysis of bacteria, thus restraining the bacterial population within a specified scope ( Din et al., 2016 ). Moreover, population competition between the intrinsic bacterial flora and orally administered GEBs is always inevitable. Once foreign bacteria dominate the original flora, they probably alter the physiology of the host, thus leading to dysfunction of the gastrointestinal tract, such as inflammation ( Spees et al., 2013 ) and pathogenic infection ( Kamada et al., 2013 ). Therefore, purging foreign bacteria from the host after treatment is another key issue in GEB application. Biocontainment strategies, alternative selection markers and the use of homologous DNA have been performed to inhibit potential transmission in the environment and purge residual foreign bacteria ( Plavec and Berlec, 2020 ). For instance, SYNB1618 must rely on exogenous diaminopimelate for cell wall synthesis in the case of dapA gene deletion, thus ensuring the complete purge of the bacteria after treatment ( Isabella et al., 2018 ).

GEB preclinical and clinical applications in disease management

As early as 100 years ago, bacteria were used to treat tumors and clostridial enteritis ( Coley, 1893 ; Hoffman, 2016 ). Engineered bacteria at their initial stages mainly focused on the treatment of gastrointestinal inflammation and tumors ( Steidler et al., 2000 ; Geirnaert et al., 2017 ; Zhou et al., 2018 ). Advances in genetic technology endowed GEBs with more functions and broad application prospects. An alternative method is to deliver foreign therapeutic drugs, thus alleviating the shortcomings of natural drugs in the low production level, short action time, and nonoral administration property. In this paragraph, we conclude and describe the use of GEBs for treating multiple diseases, such as IBD, obesity, diabetes and cancer, in detail ( Table 1 ).

Table 1 . Use of GEBs in disease treatment.

Gastrointestinal disease

The dysregulation of intestinal microbes induces gastrointestinal diseases and, in some cases, damages normal organs via the tissue-gut axis ( Fassarella et al., 2021 ; Lee and Chang, 2021 ). Routine supplementation with probiotics successfully improved or cured types of diseases, such as acute diarrhea ( Mu and Cong, 2019 ), IBD ( Saez-Lara et al., 2015 ; Jakubczyk et al., 2020 ), and diabetes ( Kobyliak et al., 2016 ; Razmpoosh et al., 2016 ; Kocsis et al., 2020 ; van de Wijgert and Verwijs, 2020 ; Davidson et al., 2021 ). Specifically, IBD, as an autoimmune disease, is characterized by chronic inflammation of the gastrointestinal tract and the loss of epithelial barrier integrity in the intestine ( Fakhoury et al., 2014 ). Ulcerative colitis and Crohn’s disease are both classified as IBD. IBD has a high incidence worldwide, but there is still no efficient treatment method. Considering the key role of microorganisms in the intestinal microecological balance and IBD inflammatory characteristics, an anti-inflammatory cytokine, interleukin-10, was expressed in Lactobacillus to treat chronic disease, which finally led to a 50% therapeutic efficacy in a mouse IBD model ( Steidler et al., 2000 ). Similarly, interleukin-4 (IL-4)-expressing Lactobacillus also significantly alleviated inflammatory responses caused by increased Th1 cells ( Souza et al., 2016 ). Additionally, the oral administration of interleukin-35 (IL-35) expressing E. coli obviously attenuated inflammatory damage in mouse colon tissue, thereby improving the symptoms of IBD ( Zhang et al., 2018 ). Furthermore, EcN has a long history in treating intestinal tract diseases in infants and toddlers. Using EcN to colonize and secrete intestinal trefoil factor could significantly improve the integrity of the intestinal epithelium and reduce the dextran sodium sulfate-induced intestinal inflammatory response in a mouse model ( Pedrolli et al., 2019 ).

Moreover, another potential way to treat colitis is to increase superoxide dismutase or catalase in the intestine, thereby reducing reactive oxygen species, which is a key factor in inflammation ( Hwang et al., 2020 ; Wan et al., 2022 ). Utilizing GEBs to produce foreign proteins to enhance the delivery of superoxide dismutase or catalase to the intestine successfully reduced the inflammatory reaction in a trinitrobenzene sulfonic acid-induced colitis model ( Del Carmen et al., 2014 ). Additionally, the expression of manganese superoxide dismutase in Bifidobacterium greatly decreased dextran sodium sulfate-induced IBD ( Liu et al., 2018 ). Furthermore, elastin is generally used to treat IBD because of its inhibitory effects on serine protease activity and anti-inflammatory effects ( Bermúdez-Humarán et al., 2015 ). The oral administration of elastin-expressing Lactobacillus strains exhibited a strong inhibitory effect on dextran sodium sulfate-induced IBD ( Bermúdez-Humarán et al., 2015 ). Similarly, genetically modified Lactobacillus strains could use mucosa to deliver an anti-inflammatory molecule, recombinant mouse heme oxygenase-1, and thus reduce the incidence of acute colitis ( Shigemori et al., 2015 ). In addition to IBD, GEBs have been used to express foreign proteins, such as antibacterial pancreatitis-related protein, to alleviate or treat chemotherapy-induced intestinal diseases and mucositis in mice ( Carvalho et al., 2017 ).

The specific tumor microenvironment enables the colonization of facultative anaerobic or anaerobic bacteria in the hypoxic regions of solid tumors. The use of tumor-targeting bacteria, such as Bifidobacterium ( Chen et al., 2021 ), Salmonella ( Chirullo et al., 2015 ; Kim et al., 2015 ; Li et al., 2017 ), Clostridium novyi-NT ( Roberts et al., 2014 ; Staedtke et al., 2016 ; Janku et al., 2021 ), and E. coli ( Afkhami-Poostchi et al., 2020 ; Chiang and Hong, 2021 ), to deliver various proteins, chemical molecules, preenzymes, etc. for cancer therapy is collectively referred to as bacteriolytic therapy. Detailing all anticancer GEBs is beyond the scope of this review, and this topic has been recently reviewed by others ( Badie et al., 2021 ; Huang et al., 2021 ; Kalia et al., 2021 ).

Metabolic diseases

The increasing prevalence of obesity, diabetes and other metabolic diseases in modern society places a heavy burden on medical care. These metabolic diseases are generally characterized by hyperglycemia, hyperlipidemia and high-density lipoprotein, and simultaneously, they could trigger each other ( Guo, 2014 ). Notably, most patients with metabolic diseases must take drugs for the rest of their lives to alleviate or slow disease progression. In contrast, the oral administration of GEBs has exhibited few side effects and better acceptance. Indeed, many GEBs have already been constructed and evaluated for curing inborn or acquired metabolic diseases.

Diabetes is one of the greatest public health problems worldwide and causes a substantial burden on the socioeconomic development of the world ( Lin et al., 2020 ). Diabetes is clinically divided into type 1 diabetes (T1D) and type 2 diabetes (T2D; Zimmet et al., 2014 ). The treatment for T1D relies on the regular injection of insulin to slow the progression of the diabetic process ( Miller et al., 2015 ), whereas T2D patients take hypoglycemic drugs, such as metformin, to restrain disease progression. However, the long-term use of glucose-lowering drugs usually results in serious side effects and economic burdens ( Khunti et al., 2019 ). Numerous studies have found that disease progression in T2D is closely associated with an imbalance in gut microflora ( Forslund et al., 2015 ). Therefore, the regulation of the intestine microenvironment using probiotics or GEBs could be an alternative strategy to cure or slow diabetes, especially T2D. Given the underlying mechanisms of diabetes, treatment could be achieved by using an engineered bacterium to produce proteins with hypoglycemic effects. For example, glucagon-like peptide 1 (GLP-1) is an efficient drug for diabetes treatment, but its short half-life time and high cost greatly prevent its extensive clinical use. However, GEBs characterized by gut colonization have the potential to address the above problems. Leveraging GLP-1 (1–37) with the ability to transfer intestinal epithelial cells into insulin-secreting cells ( Duan et al., 2015 ), GLP-1-expressing Lactobacillus successfully normalized blood glucose levels in diabetic Goto-Kakizaki rats ( Lin et al., 2016 ). Other proteins or compounds against diabetes can also achieve similar therapeutic effects by using probiotics as delivery vectors. For example, recombinant Lactobacillus expressing heat shock protein 65 and IA2P2 (a 23 amino acid peptide) effectively alleviated the symptoms of pancreatitis and improved diabetes by inhibiting the antigen-specific proliferation of T cells in T1D and regulating the balance between Th17/Tregs and Th1/Th2 cells ( Liu et al., 2016 ).

Obesity is a complex multifactorial disease and a key factor in other chronic diseases, such as cardiovascular disease, cancer, and diabetes ( Pan et al., 2021 ). Generally, obesity occurs in middle-aged and elderly people. Increasing reports demonstrate that the prevalence of obesity in children and adolescents aged 2 to 19 years has been gradually increasing worldwide, especially in developed countries ( Fryar et al., 2018 , 2020 ). Most traditional anti-obesity drugs, such as sibutramine and orlistat, act by suppressing appetite or blocking the absorption of body fat, but they produce obvious adverse effects on normal physiological function ( Huang et al., 2019 ). Fortunately, several studies have developed GEBs to express anti-obesity factors for the purpose of alleviating obesity. For instance, GLP-1-expressing Lactobacillus could reduce the incidence of high-fat diet-induced obesity in mice by restraining lipid accumulation, enhancing GLP-1 resistance to glucose intolerance, and increasing the expression of genes involved in the triglyceride degradation pathway ( Wang et al., 2021 ). Additionally, Bacillus subtilis SCK6 utilized Coenzyme A transferase acetate to increase butyric acid production and stimulate the butyric acid kinase pathway, thus attenuating hepatic steatosis and fat accumulation in high-fat diet mice ( Bai et al., 2020 ). Similarly, interleukin-22 (IL-22)-expressing Lactobacillus reuteri obviously decreased the incidence of nonalcoholic fatty liver disease in high-fat diet mice ( Oh et al., 2020 ).

Hyperammonemia, phenylketonuria and other metabolic diseases

Hyperammonemia, as a metabolic disease, is used to describe patients with high levels of plasma ammonia levels (>50 μmol/l in adults and >100 μmol/l in the neonatal period). Under normal circumstances, ammonia is mainly produced in the intestine and excreted by the liver, but severe metabolic disorders probably induce the massive accumulation of ammonia in the body and, thus, affect the urea cycle and may even trigger hepatic encephalopathy ( Auron and Brophy, 2012 ). The current treatment strategies for patients with hyperammonemia include hemodialysis, peritoneal dialysis, and antibiotic therapy. However, these treatments greatly increase infection probabilities and lead to drug resistance ( Matoori and Leroux, 2015 ). However, oral probiotic use could significantly decrease ammonia levels in mice with hepatic encephalopathy ( Lunia et al., 2014 ), demonstrating the feasibility of establishing GEBs to treat Hyperammonemia. In addition, by deleting the negative regulator of I-arginine synthesis and adding a feedback-resistant I-arginine biosynthetic enzyme in EcN, GEBs successfully achieved the conversion of NH3 to I-arginine in bacteria, thereby blocking ammonia accumulation in vivo and slowing Hyperammonemia progression ( Kurtz et al., 2019 ).

Phenylketonuria is an autosomal recessive genetic disease characterized by mental and growth retardation. Phenylketonuria results from the gene deficiency of phenylalanine hydroxyls, thus preventing the conversion of phenylalanine to tyrosine. The Phenylketonuria therapeutic methods include dietary restriction, gene therapy, and enzyme replacement. However, even a well-controlled diet cannot completely prevent the occurrence of psychiatric problems in Phenylketonuria patients, while gene therapy is extremely costly, and enzyme replacement therapy is obviously affected by the drug dose and administration schedule ( Camp et al., 2014 ). However, probiotics have the potential to be modified to produce deficient phenylalanine hydroxyl enzymes to supplement physiological requirements. The insertion of the genes of phenylalanine-ammonia-lyase and L-amino acid deaminase into the EcN genome enables probiotics to convert phenylalanine into trans-cinnamic acid salt in the gastrointestinal tract, thus leading to a 38% reduction in orally administered phenylalanine in blood ( Isabella et al., 2018 ; Puurunen et al., 2021 ).

Furthermore, hypertension is a common chronic disease that is not only a major cause of cardiovascular disease but also damages the brain, kidney, and other organs ( Fuchs and Whelton, 2020 ). Many therapeutic agents, including β-blockers, calcium channel blockers, diuretics, and renin-angiotensin converting enzyme inhibitors, have been developed to treat hypertension. However, the long-term use of these antihypertensive drugs often leads to potential side effects, such as arterial damage, angioedema, arrhythmias, impotence, hyperkalemia, and cough. More importantly, some drugs, such as angiotensin-converting enzyme inhibitory peptides, require large doses to exert therapeutic effects because their activity is inclined to be inhibited by other enzymes ( Laurent, 2017 ). However, probiotics engineered to express the enzyme have the potential to address this issue. For example, the introduction of the genes encoding tuna frame protein and yellowfin sole frame protein into Lactobacillus plantarum NC8 enabled the probiotics to synthesize angiotensin-converting enzyme inhibitory peptides, and the oral administration of angiotensin-converting enzyme inhibitory peptides significantly reduced systolic blood pressure and triglyceride levels in a spontaneously hypertensive mouse model, displaying good antihypertensive ability ( Yang et al., 2015 ).

Conclusion and prospects

Microbes have been implicated in almost all fundamental activities of physiological homeo stasis. One example of the increasingly important role of bacteriotherapy is the regulation of the intestinal flora for curing intestinal diseases and adjuvant therapy of other diseases, such as cancer and metabolic diseases ( Andrade-Oliveira et al., 2015 ; Alexander et al., 2017 ; Yuan et al., 2018 ; Molina et al., 2021 ; Si et al., 2021 ). Notably, advances in gene sequencing technologies have partly revealed the mysteries of human microbes and the interaction between microbes and various mammalian cells, greatly advancing GEB preclinical studies. To date, most existing therapeutic GEBs have been modified from human intestinal probiotics, demonstrating their potential safety compared to traditional chemical drugs, especially for long-term use. GEBs are not only effective therapeutic agents against chronic diseases due to their intestinal colonization ability but also expand the scope of the application of tumor-targeting treatment.

The use of engineered bacteria in disease treatment is still in the infancy stage and has limitations for incurable diseases. In addition, the clinical translation of GEBs is still hindered by potential pathogenicity and local laws and regulations, which only allow clinical trials to use bacteria without any genetic modification. A future challenge will be to determine whether the genetically inserted genes of GEBs could spill over into the genomes of other bacteria or mammalian cells; how GEBs could stably colonize and produce the expected substrates in the targeted sites; how they interact with the intestinal flora, thus normalizing them into the health status; and how to lock them into the expected tissues and clear them once they accomplish their mission. Such questions underscore the importance of investigating the genetic stability of the inserted genes in GEBs under normal physiological conditions. However, as biological technologies continue to evolve, newly available bacterial tools and the upgrading of therapeutic strategies of GEBs will further alleviate potential safety concerns and enhance their depth and breadth in disease prevention and treatment.

Collectively, given the importance of the microbiota in normal physiological function, the long historical use of probiotics and bacterial-derived products for health care, and our increasingly better understanding of the mechanisms underlying the various gut-brain similar axes, we expect that GEBs will make an important contribution to the prevention and treatment of various diseases that current drugs cannot address or cause serious side effects.

Author contributions

YL, JF, and HP searched references and drafted the manuscript. XZ and YZ conceived, supervised, and improved the manuscript. All authors contributed to the article and approved the submitted version.

This research was supported by the National Natural Science Foundation of China (grant no. 81971726) and the Nanjing Healthcare Science and Technology Development Special Funded Project (YKK20191).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

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Keywords: bacteriotherapy, genetically engineered bacterium, clinical application, synthetic biotechnology, heterologous expression

Citation: Liu Y, Feng J, Pan H, Zhang X and Zhang Y (2022) Genetically engineered bacterium: Principles, practices, and prospects. Front. Microbiol . 13:997587. doi: 10.3389/fmicb.2022.997587

Received: 19 July 2022; Accepted: 23 September 2022; Published: 13 October 2022.

Reviewed by:

Copyright © 2022 Liu, Feng, Pan, Zhang and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Xiuwei Zhang, [email protected] ; Yunlei Zhang, [email protected]

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

12.3 Whole Genome Methods and Pharmaceutical Applications of Genetic Engineering

Learning objectives.

By the end of this section, you will be able to:

• Explain the uses of genome-wide comparative analyses
• Summarize the advantages of genetically engineered pharmaceutical products

Advances in molecular biology have led to the creation of entirely new fields of science. Among these are fields that study aspects of whole genomes, collectively referred to as whole-genome methods. In this section, we’ll provide a brief overview of the whole-genome fields of genomics, transcriptomics, and proteomics.

Genomics, Transcriptomics, and Proteomics

The study and comparison of entire genomes, including the complete set of genes and their nucleotide sequence and organization, is called genomics . This field has great potential for future medical advances through the study of the human genome as well as the genomes of infectious organisms. Analysis of microbial genomes has contributed to the development of new antibiotics, diagnostic tools, vaccines, medical treatments, and environmental cleanup techniques.

The field of transcriptomics is the science of the entire collection of mRNA molecules produced by cells. Scientists compare gene expression patterns between infected and uninfected host cells, gaining important information about the cellular responses to infectious disease. Additionally, transcriptomics can be used to monitor the gene expression of virulence factors in microorganisms, aiding scientists in better understanding pathogenic processes from this viewpoint.

When genomics and transcriptomics are applied to entire microbial communities, we use the terms metagenomics and metatranscriptomics , respectively. Metagenomics and metatranscriptomics allow researchers to study genes and gene expression from a collection of multiple species, many of which may not be easily cultured or cultured at all in the laboratory. A DNA microarray (discussed in the previous section) can be used in metagenomics studies.

Another up-and-coming clinical application of genomics and transcriptomics is pharmacogenomics , also called toxicogenomics , which involves evaluating the effectiveness and safety of drugs on the basis of information from an individual’s genomic sequence. Genomic responses to drugs can be studied using experimental animals (such as laboratory rats or mice) or live cells in the laboratory before embarking on studies with humans. Changes in gene expression in the presence of a drug can sometimes be an early indicator of the potential for toxic effects. Personal genome sequence information may someday be used to prescribe medications that will be most effective and least toxic on the basis of the individual patient’s genotype.

The study of proteomics is an extension of genomics that allows scientists to study the entire complement of proteins in an organism, called the proteome . Even though all cells of a multicellular organism have the same set of genes, cells in various tissues produce different sets of proteins. Thus, the genome is constant, but the proteome varies and is dynamic within an organism. Proteomics may be used to study which proteins are expressed under various conditions within a single cell type or to compare protein expression patterns between different organisms.

The most prominent disease being studied with proteomic approaches is cancer, but this area of study is also being applied to infectious diseases. Research is currently underway to examine the feasibility of using proteomic approaches to diagnose various types of hepatitis, tuberculosis, and HIV infection, which are rather difficult to diagnose using currently available techniques. 5

A recent and developing proteomic analysis relies on identifying proteins called biomarkers , whose expression is affected by the disease process. Biomarkers are currently being used to detect various forms of cancer as well as infections caused by pathogens such as Yersinia pestis and Vaccinia virus . 6

Other “-omic” sciences related to genomics and proteomics include metabolomics, glycomics, and lipidomics, which focus on the complete set of small-molecule metabolites, sugars, and lipids, respectively, found within a cell. Through these various global approaches, scientists continue to collect, compile, and analyze large amounts of genetic information. This emerging field of bioinformatics can be used, among many other applications, for clues to treating diseases and understanding the workings of cells.

Additionally, researchers can use reverse genetics , a technique related to classic mutational analysis , to determine the function of specific genes. Classic methods of studying gene function involved searching for the genes responsible for a given phenotype. Reverse genetics uses the opposite approach, starting with a specific DNA sequence and attempting to determine what phenotype it produces. Alternatively, scientists can attach known genes (called reporter genes) that encode easily observable characteristics to genes of interest, and the location of expression of such genes of interest can be easily monitored. This gives the researcher important information about what the gene product might be doing or where it is located in the organism. Common reporter genes include bacterial lacZ , which encodes beta-galactosidase and whose activity can be monitored by changes in colony color in the presence of X-gal as previously described, and the gene encoding the jellyfish protein green fluorescent protein (GFP) whose activity can be visualized in colonies under ultraviolet light exposure ( Figure 12.26 ).

Check Your Understanding

• How is genomics different from traditional genetics?
• If you wanted to study how two different cells in the body respond to an infection, what –omics field would you apply?
• What are the biomarkers uncovered in proteomics used for?

Clinical Focus

Because Kayla’s symptoms were persistent and serious enough to interfere with daily activities, Kayla’s physician decided to order some laboratory tests. The physician collected samples of Kayla’s blood, cerebrospinal fluid (CSF), and synovial fluid (from one of her swollen knees) and requested PCR analysis on all three samples. The PCR tests on the CSF and synovial fluid came back positive for the presence of Borrelia burgdorferi , the bacterium that causes Lyme disease .

Kayla’s physician immediately prescribed a full course of the antibiotic doxycycline . Fortunately, Kayla recovered fully within a few weeks and did not suffer from the long-term symptoms of post-treatment Lyme disease syndrome (PTLDS), which affects 10–20% of Lyme disease patients. To prevent future infections, Kayla’s physician advised her to use insect repellant and wear protective clothing during her outdoor adventures. These measures can limit exposure to Lyme-bearing ticks, which are common in many regions of the United States during the warmer months of the year. Kayla was also advised to make a habit of examining herself for ticks after returning from outdoor activities, as prompt removal of a tick greatly reduces the chances of infection.

Lyme disease is often difficult to diagnose. B. burgdorferi is not easily cultured in the laboratory, and the initial symptoms can be very mild and resemble those of many other diseases. But left untreated, the symptoms can become quite severe and debilitating. In addition to two antibody tests, which were inconclusive in Kayla’s case, and the PCR test, a Southern blot could be used with B. burgdorferi -specific DNA probes to identify DNA from the pathogen. Sequencing of surface protein genes of Borrelia species is also being used to identify strains within the species that may be more readily transmitted to humans or cause more severe disease.

Go back to the previous Clinical Focus box.

Recombinant DNA Technology and Pharmaceutical Production

Genetic engineering has provided a way to create new pharmaceutical products called recombinant DNA pharmaceuticals . Such products include antibiotic drugs, vaccines, and hormones used to treat various diseases. Table 12.1 lists examples of recombinant DNA products and their uses.

For example, the naturally occurring antibiotic synthesis pathways of various Streptomyces spp., long known for their antibiotic production capabilities, can be modified to improve yields or to create new antibiotics through the introduction of genes encoding additional enzymes. More than 200 new antibiotics have been generated through the targeted inactivation of genes and the novel combination of antibiotic synthesis genes in antibiotic-producing Streptomyces hosts. 7

Genetic engineering is also used to manufacture subunit vaccines , which are safer than other vaccines because they contain only a single antigenic molecule and lack any part of the genome of the pathogen (see Vaccines ). For example, a vaccine for hepatitis B is created by inserting a gene encoding a hepatitis B surface protein into a yeast; the yeast then produces this protein, which the human immune system recognizes as an antigen. The hepatitis B antigen is purified from yeast cultures and administered to patients as a vaccine. Even though the vaccine does not contain the hepatitis B virus, the presence of the antigenic protein stimulates the immune system to produce antibodies that will protect the patient against the virus in the event of exposure. 8 9

Genetic engineering has also been important in the production of other therapeutic proteins, such as insulin , interferons , and human growth hormone , to treat a variety of human medical conditions. For example, at one time, it was possible to treat diabetes only by giving patients pig insulin, which had supply limitations and caused allergic reactions due to small differences between the proteins expressed in human and pig insulin. Villa-Komaroff's and the Gilbert team's groundbreaking methods changed that. After they demonstrated the process for producing the hormone, the FDA approved the resulting synthetic insulin for human use. And since 1982, recombinant DNA technology has been used to produce large-scale quantities of human insulin using E. coli in a relatively inexpensive process that yields a more consistently effective pharmaceutical product. Scientists have also genetically engineered E. coli capable of producing human growth hormone (HGH), which is used to treat growth disorders in children and certain other disorders in adults. The HGH gene was cloned from a cDNA library and inserted into E. coli cells by cloning it into a bacterial vector. Eventually, genetic engineering will be used to produce DNA vaccines and various gene therapies, as well as customized medicines for fighting cancer and other diseases.

• What bacterium has been genetically engineered to produce human insulin for the treatment of diabetes?
• Explain how microorganisms can be engineered to produce vaccines.

RNA Interference Technology

In Structure and Function of RNA , we described the function of mRNA, rRNA, and tRNA. In addition to these types of RNA, cells also produce several types of small noncoding RNA molecules that are involved in the regulation of gene expression. These include antisense RNA molecules, which are complementary to regions of specific mRNA molecules found in both prokaryotes and eukaryotic cells. Non-coding RNA molecules play a major role in RNA interference (RNAi) , a natural regulatory mechanism by which mRNA molecules are prevented from guiding the synthesis of proteins. RNA interference of specific genes results from the base pairing of short, single-stranded antisense RNA molecules to regions within complementary mRNA molecules, preventing protein synthesis. Cells use RNA interference to protect themselves from viral invasion, which may introduce double-stranded RNA molecules as part of the viral replication process ( Figure 12.27 ).

Researchers are currently developing techniques to mimic the natural process of RNA interference as a way to treat viral infections in eukaryotic cells. RNA interference technology involves using small interfering RNAs (siRNAs) or microRNAs (miRNAs) ( Figure 12.28 ). siRNAs are completely complementary to the mRNA transcript of a specific gene of interest while miRNAs are mostly complementary. These double-stranded RNAs are bound to DICER, an endonuclease that cleaves the RNA into short molecules (approximately 20 nucleotides long). The RNAs are then bound to RNA-induced silencing complex (RISC), a ribonucleoprotein. The siRNA-RISC complex binds to mRNA and cleaves it. For miRNA, only one of the two strands binds to RISC. The miRNA-RISC complex then binds to mRNA, inhibiting translation. If the miRNA is completely complementary to the target gene, then the mRNA can be cleaved. Taken together, these mechanisms are known as gene silencing .

• 5 E.O. List, D.E. Berryman, B. Bower, L. Sackmann-Sala, E. Gosney, J. Ding, S. Okada, and J.J. Kopchick. “The Use of Proteomics to Study Infectious Diseases.” Infectious Disorders-Drug Targets (Formerly Current Drug Targets-Infectious Disorders ) 8 no. 1 (2008): 31–45.
• 6 Mohan Natesan, and Robert G. Ulrich. “Protein Microarrays and Biomarkers of Infectious Disease.” International Journal of Molecular Sciences 11 no. 12 (2010): 5165–5183.
• 7 Jose-Luis Adrio and Arnold L. Demain. “Recombinant Organisms for Production of Industrial Products.” Bioengineered Bugs 1 no. 2 (2010): 116–131.
• 8 U.S. Department of Health and Human Services. “Types of Vaccines.” 2013. http://www.vaccines.gov/more_info/types/#subunit. Accessed May 27, 2016.
• 9 The Internet Drug List. Recombivax . 2015. http://www.rxlist.com/recombivax-drug.htm. Accessed May 27, 2016.

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Genetic engineering articles from across Nature Portfolio

Genetic engineering is the act of modifying the genetic makeup of an organism. Modifications can be generated by methods such as gene targeting, nuclear transplantation, transfection of synthetic chromosomes or viral insertion. Selective breeding is not considered a form of genetic engineering.

Genome editing with DNA-dependent polymerases

Two CRISPR tools harness DNA-dependent polymerases for genome editing — and may overcome some limitations of prime editors.

• Quinn T. Cowan
• Alexis C. Komor

Latest Research and Reviews

Unbiased screening identifies regulators of cell-cell adhesion and treatment options in pemphigus

Cell-cell adhesion by desmosomes is weakened in the blistering skin disease pemphigus vulgaris. Here, authors found that the transcription factor Kruppel-like factor 5 is essential for the expression of the desmosomal gene desmoglein 3 and suggest a novel treatment approach.

• Henriette Franz
• Maitreyi Rathod
• Volker Spindler

Population suppression by release of insects carrying a dominant sterile homing gene drive targeting doublesex in Drosophila

CRISPR homing gene drives can suppress pest populations by targeting female fertility genes, converting wild-type alleles into drive alleles in the germline of drive heterozygotes. Here the authors demonstrate a genetic pest suppression system based on dominant female-sterile doublesex alleles and show that releases of transgenic males eliminated Drosophila cage populations, with modelling showing improved performance compared to similar systems.

• Weizhe Chen
• Jialiang Guo
• Jackson Champer

PGC-based cryobanking, regeneration through germline chimera mating, and CRISPR/Cas9-mediated TYRP1 modification in indigenous Chinese chickens

The combination of efficient PGC culture, practical cryopreservation, regeneration from recipient chickens, and CRISPR/Cas9 gene-editing to create knockout chickens for conserving and genetically improving rare native breeds.

• Keiji Kinoshita
• Kumiko Tanabe
• Hong-Jiang Wei

Expanding the CRISPR base editing toolbox in Drosophila melanogaster

Testing three types of cytosine base editors in fruit flies demonstrates the potential usage of these base editors in genetic biocontrol strategies, with the rAPO-1 achieving high editing efficiency (~99%) with no detectable INDEL mutations.

• Michael Clark
• Christina Nguyen
• Víctor López Del Amo

Optimized dicot prime editing enables heritable desired edits in tomato and Arabidopsis

This study enhanced prime editing (PE) for dicot plants using new combinations of PE components delivered by a geminiviral replicon. This achieved up to 38.2% PE efficiency in tomatoes and Arabidopsis , enabling precise breeding applications in dicots.

• Tien Van Vu
• Ngan Thi Nguyen
• Jae-Yean Kim

A user-friendly CRISPR/Cas9 system for mutagenesis of Neurospora crassa

• Stefanie Grüttner
• Frank Kempken

News and Comment

A safety guide for transgenic Cre drivers in metabolism

Despite the high utility and widespread use of Cre driver lines, lack of Cre specificity, Cre-induced toxicity or poor experimental design can affect experimental results and conclusions. Such pitfalls must be considered before embarking on any Cre-based studies in metabolic research.

• Carla Horvath
• Christian Wolfrum
• Pawel Pelczar

Embedding AI in biology

Advanced artificial intelligence approaches are rapidly transforming how biological data are acquired and analyzed.

Precise and versatile genome editing with click editors

We developed click editors, comprising HUH endonucleases, DNA-dependent DNA polymerases and CRISPR–Cas9 nickases, which together enable programmable precision genome engineering from simple DNA templates.

Using gene copy flexibility to build adaptable synthetic microbial populations

Plasmid coupling creates heterogeneity in copy number and, therefore, expression across a microbial population. We demonstrate that plasmid-encoded fitness differences between individuals can then lead to adaptation of the population to specific environments and can promote both genetic stability and memory of past environmental exposures.

RNA editing with CRISPR

• Petra Gross

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• National Center for Biotechnology Information - PubMed Central - Genetic engineering of animals: Ethical issues, including welfare concerns
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• Table Of Contents

genetic engineering , the artificial manipulation, modification, and recombination of DNA or other nucleic acid molecules in order to modify an organism or population of organisms. The term genetic engineering is generally used to refer to methods of recombinant DNA technology , which emerged from basic research in microbial genetics . The techniques employed in genetic engineering have led to the production of medically important products, including human insulin , human growth hormone , and hepatitis B vaccine , as well as to the development of genetically modified organisms such as disease-resistant plants.

The term genetic engineering initially referred to various techniques used for the modification or manipulation of organisms through the processes of heredity and reproduction . As such, the term embraced both artificial selection and all the interventions of biomedical techniques, among them artificial insemination , in vitro fertilization (e.g., “test-tube” babies), cloning , and gene manipulation. In the latter part of the 20th century, however, the term came to refer more specifically to methods of recombinant DNA technology (or gene cloning ), in which DNA molecules from two or more sources are combined either within cells or in vitro and are then inserted into host organisms in which they are able to propagate .

The possibility for recombinant DNA technology emerged with the discovery of restriction enzymes in 1968 by Swiss microbiologist Werner Arber . The following year American microbiologist Hamilton O. Smith purified so-called type II restriction enzymes , which were found to be essential to genetic engineering for their ability to cleave a specific site within the DNA (as opposed to type I restriction enzymes, which cleave DNA at random sites). Drawing on Smith’s work, American molecular biologist Daniel Nathans helped advance the technique of DNA recombination in 1970–71 and demonstrated that type II enzymes could be useful in genetic studies. Genetic engineering based on recombination was pioneered in 1973 by American biochemists Stanley N. Cohen and Herbert W. Boyer, who were among the first to cut DNA into fragments, rejoin different fragments, and insert the new genes into E. coli bacteria , which then reproduced.

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• Introduction to Genetic Engineering and Its Applications

Lesson Introduction to Genetic Engineering and Its Applications

Grade Level: 9 (9-12)

(Consider adding 30 minutes for a thorough ethics discussion.)

Lesson Dependency: None

Subject Areas: Biology

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Genetic engineers have developed genetic recombination techniques to manipulate gene sequences in plants, animals and other organisms to express specific traits. Applications for genetic engineering are increasing as engineers and scientists work together to identify the locations and functions of specific genes in the DNA sequence of various organisms. Once each gene is classified, engineers develop ways to alter them to create organisms that provide benefits such as cows that produce larger volumes of meat, fuel- and plastics-generating bacteria, and pest-resistant crops.

After this lesson, students should be able to:

• List several present day applications of genetic engineering.
• Describe general techniques used by genetic engineers to modify DNA.
• Analyze the benefits and drawbacks of manipulating an organism's DNA.

Educational Standards Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards. All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN) , a project of D2L (www.achievementstandards.org). In the ASN, standards are hierarchically structured: first by source; e.g. , by state; within source by type; e.g. , science or mathematics; within type by subtype, then by grade, etc .

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State Standards

Texas - science.

A basic understanding of protein synthesis and DNA's role in the cell/body is helpful so students can follow how changes in DNA result in major changes in the characteristics of organisms.

(Make copies of the Genetic Engineering Flow Chart , one per student. Hand out the blank flow charts for students to fill in during the presentation and lecture. Then show the class the 16-slide Genetic Engineering Presentation , a PowerPoint® file. Open with two images of the same organism: one that has been genetically engineered and one that has not. Examples: two ears of corn in which the non-modified one is diseased; two cows in which the modified one is larger; or, since students really respond to bioluminescent organisms, show two mice in which one has been modified to glow green. Slide 2 shows two examples of modified versus non-modified mice. Another idea is to show two organisms that look the same even though one has been modified as an example of how most modifications are not visible.)

What is the difference between these two organisms? (Answers will vary, depending on the image shown.) Even though they are the same organism, why are they are different? (Answer: Genetic engineering. Some students may not come to this answer on their own. Expect some to suggest mutations.) The difference is due to genetic engineering. The animal (or plant) that has been changed is called a genetically modified organism, or GMO.

How do engineers change the traits of organisms? (Listen to student ideas.) DNA contains all of the genetic information to determine an organism's traits or characteristics. By modifying the DNA, engineers are able to determine which traits an organism will possess.

(Continue through the presentation: What is genetic engineering? History of GMO Development, What is the GMO process? Then starting with slide 6 , go through the provided examples of GMO bacteria, plants and animals. Emphasize the reasons for modifying each organism [ slide 10 ].)

(Show the slide 14 picture of a man and spider.) Can anyone guess what would happen if we combined the DNA from these two creatures? (Expect students to enthusiastically answer "spiderman.") Could engineers create a "spiderman" in the lab today? (Expect some yes responses, while most students answer no.) Not quite. However, in 2000, engineers created the first goat able to produce spider silk proteins (an amazingly strong and elastic fiber with futuristic benefits in construction [bridge suspension cables, airbags that are gentler for passengers], medicine [artificial skin to heal burns, artificial ligaments, thread for stitching wounds] and the military [body armor] if sufficient quantities could be generated), so maybe it is not too far away.

(Show slide 15 .) Genetic engineering is so new and astonishing that people are still trying to figure out the pros and cons. We saw some examples of the benefits from genetically modified organisms, what about the disadvantages and harm caused by genetic engineering? (After listening to student ideas, go through the concerns listed on the slide. Alternatively, go through the contents of this slide and background information as a class discussion during the Lesson Closure, extending the lesson time as necessary.)

(Continue on to present students with the content in the Lesson Background section, and then a class review of the completed flow charts.)

Lesson Background and Concepts for Teachers

What is DNA?

Deoxyribonucleic acid (DNA) is a large biomolecule that contains the complete genetic information for an organism. Every cell of living organisms and many viruses, contains DNA. The basic building block of a DNA molecule is called a nucleotide , and a single strand of DNA may contain billions of nucleotides. (Refer to Figure 1 to see the DNA structure with labeled parts.) Although each DNA molecule contains many of these building blocks, only four unique nucleotides are used to create the entire DNA sequence; these are written as A, G, C and T. Analogous to how the 26 letters of the alphabet can be arranged to create words with different meanings, these four nucleotides can be arranged in sequences to "spell" the genetic instructions to create all of the different proteins organisms need to live.

Why are proteins important?

Proteins perform all of the work in organisms. Some functions of proteins include:

• Serving as catalysts for reactions
• Performing cell signaling
• Transporting molecules across membranes
• Creating structures

When a protein is created by its gene, it is said that the gene is "expressed," or used. Most gene expressions do not produce results visible to the unaided eye. However some genes, such as those that code for proteins responsible for pigment, do have visual expression. The expression of a gene in an observable manner is called a phenotypic trait ; one example is an organism's hair color. In fact, everything you can see in an organism is a result of proteins or protein actions.

How is DNA used in genetic engineering?

By definition, genetic engineering is the direct altering of an organism's genome. This is achieved through manipulation of the DNA. Doing this is possible because DNA is like a universal language; all DNA for all organisms is made up of the same nucleotide building blocks. Thus, it is possible for genes from one organism to be read by another organism. In the cookbook analogy, this equates to taking a recipe from one organism's cookbook and putting into another cookbook. Now imagine that all cookbooks are written in the same language; thus, any recipe can be inserted and used in any other cookbook.

In practice, since DNA contains the genes to build certain proteins, by changing the DNA sequence, engineers are able to provide a new gene for a cell/organism to create a different protein. The new instructions may supplement the old instructions such that an extra trait is exhibited, or they may completely replace the old instructions such that a trait is changed.

Genetic Engineering Technique

The process for genetic engineering begins the same for any organism being modified (see Figure 3 for an example of this procedure).

• Identify an organism that contains a desirable gene.
• Extract the entire DNA from the organism.
• Remove this gene from the rest of the DNA. One way to do this is by using a restriction enzyme . These enzymes search for specific nucleotide sequences where they will "cut" the DNA by breaking the bonds at this location.
• Insert the new gene to an existing organism's DNA. This may be achieved through a number of different processes.

Once the recombinant DNA has been built, it can be passed to the organism to be modified. If modifying bacteria, this process is quite simple. The plasmid can be easily inserted into the bacteria where the bacteria treat it as their own DNA. For plant modification, certain bacteria such as Agrobacterium tumefaciens may be used because these bacteria permit their plasmids to be passed to the plant's DNA.

Applications and Economics

The number of applications for genetic engineering are increasing as more and more is learned about the genomes of different organisms. A few interesting or notable application areas are described below.

How many of today's crops are genetically modified? As of 2010, in the U.S., 86% of corn produced was genetically modified. Bt -corn is a common GMO that combines a gene from the Bt bacteria with corn DNA to produce a crop that is insect-resistant. The bacteria gene used contains a recipe for a protein that is toxic when consumed by insects, but safe when consumed by humans.

A number of other genes can be combined with crops to produce desirable properties such as:

• Herbicide-, drought-, freeze- or disease-resistance
• Higher yield
• Faster growth
• Improved nutrition
• Longer shelf life

The creation of genetically modified crops provides many incentives for farmers and businesses. When farmers are able to plant a crop that has a higher yield per acre, they can significantly increase production, and thus sales, with minimal cost. Disease, pest and other resistances reduce crop loss, which also helps to increase profits. Besides farmers, other benefactors from modified crops include seed, agrochemical and agriculture equipment companies as well as distributors and universities that are involved in GMO research. In 2011, the value of genetically modified seed was $13.2 billion in the U.S. alone. The value of the end products produced from these seeds topped $160 billion.

Due to their simple structures, the most commonly modified organisms are bacteria. The first modified bacteria were created in 1973. Bacteria can be modified to produce desirable proteins that can be harvested and used. One example is insulin or spider silk, which is difficult to gather naturally. Other modifications to bacteria include making changes to the cellular respiration process to alter the byproducts; typically CO 2 is produced, however engineers have made modifications so that hydrocarbon byproducts such as diesel and polyethylene (a fuel and a plastic) are produced.

(The 30-minute lesson time leaves a fair amount of time for discussion, but since class participation will vary, you may want to extend the lesson another 30-minutes to allow for a thorough discussion of the ethical implications of genetic engineering. This makes a good student research and debate topic, too.)

The main reason genetically modified organisms are not more widely used is due to ethical concerns. Nearly 50 countries around the world, including Australia, Japan and all of the countries in the European Union, have enacted significant restrictions or full bans on the production and sale of genetically modified organism food products, and 64 countries have GMO labeling requirements. Some issues to consider when deciding whether to create and/or use GMOs include:

Safety: This generally arises in the case of GMO foods. Are the foods safe for human consumption? Is GMO feed healthy for animals? Many opponents of GMO foods say not enough independent testing is done before the food is approved for sale to consumers. In general, research has shown that GMO foods are safe for humans. Another safety consideration is the health of farmers and their families, animals and communities who are put at risk with exposure to chemicals used in tandem with GMO seeds.

Environmental Impact: Consider that genetic engineers have the ability to create trees that grow faster than their unmodified counterparts. This seems like a great deal for the lumber industry, but might some unintended consequences result? Being outdoors and grown in large quantities, the modified trees may cross-pollinate with unmodified trees to form hybrids outside of designated growing areas. This in return could create trees that could disrupt the ecosystem. For example, they could overpopulate the area or grow so large that they smother other plant life. This same scenario has unintended and undesirable consequences when the pollen from GMO crops drifts into non-GMO fields.

Humans: Should humans be genetically engineered? Doing so could have medical applications that reduce or prevent genetic disorders such as Down's syndrome. However, the bigger question is where should engineering humans stop? Should parents be allowed to decide their children's eye colors, heights or even genders before birth?

Watch this activity on YouTube

What part of an organism contains all of the information needed for it to function? (Answer: DNA) When genes are expressed, what is the final product made? (Answer: Proteins) Does anyone know why bacteria are modified more than other organisms? (Answer: With their very simple structures and ability to use plasmids, bacteria are much easier and less costly to modify.)

What are some ethical and moral concerns that genetic engineers must consider? Does anyone think it is a good idea to genetically modify people? Some researchers say this could be an approach to cure diseases such as Down's syndrome and other genetic defects. Superficial changes could also be made, such as determining a person's height, eye color or gender, by making changes to embryos in the mothers' wombs. But just because something can be done, does that make it a good idea? (Answer: No. This is a good topic for an extended discussion.)

DNA: Acronym for deoxyribonucleic acid, which is a molecule that contains an organism's complete genetic information.

gene: The molecular unit of an organism that contains information for a specific trait (specific DNA sequence).

genome: An entire set of genes for an organism.

GMO: Acronym for genetically modified organism.

nucleotide: The building block of DNA.

plasmid: The circular DNA structure used by bacteria.

protein: Large biomolecules used by an organism for a number of purposes; in this context, to express a desired trait.

recombinant DNA: DNA to which a section has been removed and replaced (recombined) with a new sequence.

restriction enzyme: An enzyme that "cuts" DNA when specific base pair sequences are present.

trait: A distinguishing characteristic.

Pre-Lesson Assessment

Discussion Questions: Initiate a brief discussion to gauge whether students have heard of or know anything about genetics. Ask questions such as:

• Why are your eyes the color that they are?
• Would anyone like to be taller (or shorter)?
• Is there any way to make these changes?

Post-Introduction Assessment

Flow Chart: Have students complete the Genetic Engineering Flow Chart during the course of the lesson. After delivering the presentation and lecture, go through the flow chart as a class, so that students can complete anything they missed and check their flow charts for accuracy. Answers are provided on the Genetic Engineering Flow Chart Answer Key .

Lesson Summary Assessment

Recombinant Creature Design : Have students in pairs (or individually) create their own recombinant organisms. Direct students to pick any organism and decide what gene they would like to add. If desired, provide a list of genes from which they can choose (such as genes that makes an organism smarter, bigger, faster, grow extra limbs, etc.). To encourage critical thinking, require students to write down a potential use for the resulting creatures. Finally, have students sketch what their recombinant creatures would look like.

View some genetic engineering examples (with photographs) at: http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering/

Show students some applications of spider silk at Popular Mechanics' "6 Spider-Silk Superpowers" slide show at http://www.popularmechanics.com/science/health/med-tech/6-spider-silk-superpowers#slide-1

As a class, students work through an example showing how DNA provides the "recipe" for making human body proteins. They see how the pattern of nucleotide bases (adenine, thymine, guanine, cytosine) forms the double helix ladder shape of DNA, and serves as the code for the steps required to make gene...

Students learn about mutations to both DNA and chromosomes, and uncontrolled changes to the genetic code. They are introduced to small-scale mutations (substitutions, deletions and insertions) and large-scale mutations (deletion duplications, inversions, insertions, translocations and nondisjunction...

Students reinforce their knowledge that DNA is the genetic material for all living things by modeling it using toothpicks and gumdrops that represent the four biochemicals (adenine, thiamine, guanine, and cytosine) that pair with each other in a specific pattern, making a double helix. Student teams...

Students construct paper recombinant plasmids to simulate the methods genetic engineers use to create modified bacteria. They learn what role enzymes, DNA and genes play in the modification of organisms.

12 Bizarre Examples of Genetic Engineering. Posted October 27, 2010. MNN Holdings, Mother Nature Network. Accessed December 8, 2013. http://www.mnn.com/green-tech/research-innovations/photos/12-bizarre-examples-of-genetic-engineering

Biello, David. Turning Bacteria into Plastic Factories. Posted September 16, 2008. Scientific American. Accessed December 11, 2013. http://www.scientificamerican.com/article.cfm?id=turning-bacteria-into-plastic-factories-replacing-fossil-fuels

DNA. Updated June 7, 2014. Wikipedia, The Free Encyclopedia. Accessed June 16, 2014. http://en.wikipedia.org/wiki/DNA

Emspak, Jesse. Gut Bacteria Make Diesel Fuel. Posted April 23, 2013. Discovery Communications. Accessed December 11, 2013. http://news.discovery.com/tech/biotechnology/gut-bacteria-make-diesel-fuel-130423.htm

Genetic engineering. Updated December 7, 2013. Wikipedia, The Free Encyclopedia. Accessed December 9, 2013. http://en.wikipedia.org/wiki/Genetic_engineering

Genetically modified crops. Updated June 12, 2014. Wikipedia, The Free Encyclopedia. Accessed June 16, 2014. http://en.wikipedia.org/wiki/Genetically_modified_crops

Straley, Regan. GMO Food Concerns. Posted August 29, 2014. Lancaster Online, Lancaster, PA. Accessed August 31, 2014. http://lancasteronline.com/opinion/gmo-food-concerns/article_3c5092ba-2ed0-11e4-ab00-001a4bcf6878.html

Vierra, Craig, et al. The Future of Biomaterial Manufacturing: Spider Silk Production from Bacteria. Posted July 17, 2012. Journal of Visualized Experiments (JoVE). Accessed December 11, 2013. http://www.jove.com/about/press-releases/39/the-future-biomaterial-manufacturing-spider-silk-production-from

What is genetic engineering and how does it work? Updated 2005. University of Nebraska. Accessed December 10, 2013. http://agbiosafety.unl.edu/basic_genetics.shtml

Other Related Information

(optional: Show students the What Is Engineering? video)

Contributors

Supporting program, acknowledgements.

This digital library content was developed by the University of Houston's College of Engineering under National Science Foundation GK-12 grant number DGE 0840889. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.

Last modified: May 12, 2021

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Revolutionizing Medical Microbiology: How Molecular and Genomic Approaches Are Changing Diagnostic Techniques

Poyasha a goyal.

1 Microbiology, Datta Meghe Medical College, Datta Meghe Institute of Higher Education and Research (DU), Wardha, IND

Nandkishor J Bankar

2 Microbiology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research (DU), Wardha, IND

Vaishnavi H Mishra

Sonali k borkar.

3 Community Medicine, Datta Meghe Medical College, Datta Meghe Institute of Higher Education and Research (DU), Wardha, IND

Jagadish G Makade

4 Community Medicine, Datta Meghe Medical College, Datta Meghe Institute of Medical Sciences(DU), Wardha, IND

Molecular and genomic approaches have revolutionized medical microbiology by offering faster and more accurate diagnostic techniques for infectious diseases. Traditional methods, which include culturing microbes and biochemical testing, are time-consuming and may not detect antibiotic-resistant strains. In contrast, molecular and genomic methods, including polymerase chain reaction (PCR)-based techniques and whole-genome sequencing, provide rapid and precise detection of pathogens, early-stage diseases, and antibiotic-resistant strains. These approaches have advantages such as high sensitivity and specificity, the potential for targeted therapies, and personalized medicine. However, implementing molecular and genomic techniques faces challenges related to cost, equipment, expertise, and data analysis. Ethical and legal considerations regarding patient privacy and genetic data usage also arise. Nonetheless, the future of medical microbiology lies in the widespread adoption of molecular and genomic approaches, which can lead to improved patient outcomes and the identification of antibiotic-resistant strains. Continued advancements, education, and exploration of ethical implications are necessary to fully harness the potential of molecular and genomic techniques in medical microbiology.

Introduction and background

The healthcare system depends heavily on the science of diagnostics because it serves as the basis for medical judgment. Diagnostic tests provide crucial data that inform personalized cancer treatments, assist in choosing the best antibiotics to treat infections, and offer insightful information on every aspect of healthcare, including disease management, prevention, detection, diagnosis, and treatment [ 1 ]. Clinical chemistry, immunology, hematology, microbiology, and molecular diagnostics are some of the primary diagnostic categories. Among these, molecular diagnostics has attracted a lot of attention recently because of its capacity to offer comprehensive insights into diagnosis as well as therapy modalities. This field has experienced significant changes, revolutionizing healthcare by deeply understanding various illness states [ 2 ]. Advanced technologies are used in molecular diagnostics to find and examine genetic and molecular changes linked to diseases. To better understand and treat a variety of medical diseases, molecular diagnostics has created new pathways for study and treatment by analyzing people's genetic makeup [ 3 ]. Specific diseases and disorders have been addressed for in-depth examination and therapy in the field of molecular diagnostics. This method has made it possible to create precise and personalized therapies based on a person's genetic profile, increasing the effectiveness and results of treatments. Particularly helpful applications of molecular diagnostics include oncology, infectious diseases, genetic abnormalities, and personalized treatment [ 4 ]. Two novel therapeutic modalities, pharmacogenomics, and nutrigenomics, have also been made possible by the science of molecular diagnostics. Pharmacogenomics entails examining a person's genetic variants to ascertain how they will react to specific pharmaceuticals, optimizing treatment regimens, and reducing negative drug reactions. Nutrigenomics, on the other hand, investigates how a person's genes and diet interact, enabling tailored nutritional recommendations that can have an impact on disease management techniques [ 5 , 6 ]. Diagnostics and healthcare have undergone a paradigm shift due to molecular diagnostics. Utilizing cutting-edge technologies and expanding our knowledge of genetic and molecular variables has changed medical research, diagnosis, and treatment methods. The potential of molecular diagnostics in creating tailored and successful disease treatment strategies is further highlighted by the development of nutrigenomics and pharmacogenomics [ 7 , 8 ]. The objective of this review is to explore molecular and genomic techniques' potential for improving medical microbiology.

Search strategy

We used the PubMed and Scopus advanced search strategy to obtain articles from PubMed and Scopus employing the following terms: (“molecular diagnostic techniques” OR “genomic diagnostic techniques” OR “traditional diagnostic techniques" or "molecular and genomic approaches” OR “traditional diagnostic techniques” OR “molecular and genomic approaches” OR “advantages of molecular and genomic approaches in medical microbiology” OR “strengths molecular and genomic approaches” OR “limitations molecular and genomic approaches”). We obtained the most pertinent research papers and used them in different arrangements using the Boolean operators “AND” and “OR.” 

Search outcomes

After conducting the initial search, we identified a total of 965 articles across the searched databases. We then excluded duplicates (n=400) and conducted an initial screening of titles and abstracts, which excluded a further 565 articles. After the full-text screening of the remaining 360 articles, we excluded 149 articles for not meeting the inclusion criteria; the full free text was not available and was not written in English, leaving a total of 56 articles for the final review (Figure ​ (Figure1 1 ).

PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses; n: number of studies

The timeline illustrates key milestones in the field of molecular diagnostics. Pauling's term "molecular disease" in 1949 linked genetics to sickle cell anemia. The 1980s saw prenatal tests using deoxyribonucleic acid-cutting enzymes. Companies like Molecular Diagnostics Inc. emerged, followed by gene discoveries and sequencing techniques in the 1990s. The Association for Molecular Pathology (AMP) was formed in 1995; the European Union (EU) allowed gene patents in 1998; and journals like The Journal of Medical Diagnostics started. Legal battles over gene patents occurred, including the 2013 United States Supreme Court ruling against patenting natural gene sequences. The history of molecular and genomic technique advancements is mentioned in Table ​ Table1 1 .

DNA: deoxyribonucleic acid; AMP: Association for Molecular Pathology; BRCA1: BReast CAncer gene 1; BRCA2: BReast CAncer gene 2; RNA: ribonucleic acid; CRISPR: clustered regularly interspaced short palindromic repeats

Traditional diagnostic techniques versus molecular and genomic approaches

Traditional diagnostic techniques for infectious diseases include culturing microbes on agar plates, biochemical testing, and microscopic examination of samples. These methods are slow, often taking days or weeks to yield results, and they may not be able to identify the causative agent of infection [ 12 ]. Additionally, traditional diagnostic techniques may be unable to detect antibiotic-resistant strains of bacteria, which can lead to inappropriate treatment and potentially fatal outcomes [ 13 , 14 ]. Traditional methods' primary drawback is how time-consuming they are. To allow for the growth and identification of organisms, an incubation duration of several days or even weeks is necessary when cultivating bacteria on agar plates. This wait for findings can delay the start of therapy, which can be harmful, especially in cases of serious or life-threatening infections [ 15 ].

In contrast, molecular and genomic approaches offer faster and more accurate results and can detect antibiotic-resistant strains of bacteria [ 16 ]. These methods entail isolating nucleic acids from a patient's sample, such as blood or tissue, and using molecular and genomic instruments to pinpoint the infection's causal culprit. These techniques include bioinformatics, whole-genome sequencing (WGS), and polymerase chain reaction (PCR) [ 17 ]. The DNA testing was significantly accelerated and made more efficient thanks to next-generation sequencing (NGS), which offered a strong alternative for identifying mutations [ 18 ].

Advantages of molecular and genomic approaches

In comparison to conventional diagnostic methods, molecular and genomic approaches have several advantages (Table ​ (Table2 2 ).

These methods are quicker and more precise. While whole-genome sequencing can offer a thorough examination of all the bacteria present in a sample, PCR-based approaches can pinpoint the infection's primary cause in a matter of hours. Early and more focused treatment of infections is made possible by this speed and accuracy, which can improve patient outcomes [ 19 , 20 ]. Traditional diagnostic methods are less sensitive and specific than molecular and genomic approaches. These techniques can identify microorganisms at low concentrations that conventional techniques can miss [ 21 ]. Furthermore, molecular and genomic techniques can be used to identify particular strains of bacteria, viruses, and fungi, which can be very helpful in infectious disease epidemics [ 22 ].

Antibiotic-resistant bacterial strains can be found using molecular and genomic methods. These strains are spreading more widely, and conventional diagnostic methods might not be able to distinguish them. Antibiotic-resistant genes can be found using molecular and genomic methods, allowing for effective infection therapy [ 23 , 24 ].

Molecular and genomic techniques in the diagnosis of infectious diseases

Molecular and genomic techniques are being used in the diagnosis of a wide range of infectious diseases [ 25 ]. Polymerase chain reaction-based methods are commonly used to diagnose viral infections, such as human immunodeficiency virus (HIV), hepatitis, and influenza [ 26 ]. These methods can also be used to diagnose bacterial infections, such as tuberculosis, chlamydia, and gonorrhea [ 27 ]. Another method that is rapidly being employed in medical microbiology is whole-genome sequencing. This technique includes sequencing every piece of DNA found in a sample of microorganisms, which can produce a thorough examination of every bacterium present [ 28 ]. When infectious disease outbreaks occur, whole-genome sequencing can be very helpful in locating the outbreak origin and monitoring the disease progress [ 29 ].

Nucleic acid amplification test 

The gold standard for amplification procedures in diagnostics is PCR. Since the method's initial publication in 1985 [ 30 ]. In medical microbiology, PCR-based methods are frequently employed to identify bacterial and viral illnesses. These procedures entail amplifying particular DNA sequences from a patient's sample, which can then be found using a variety of techniques, including gel electrophoresis or fluorescence. Gene analysis, the diagnosis of numerous genetic illnesses, and the detection of bacterial, viral, and fungal infections have all greatly benefited from the invention of methods for amplifying DNA segments [ 31 - 34 ]. Polymerase chain reaction-based methods are quick and accurate, and they can find small amounts of bacteria [ 35 ]. The detection of bacterial strains resistant to antibiotics is also possible using PCR-based methods. These strains frequently possess particular genes that confer antibiotic resistance, and PCR-based methods can identify the presence of these genes. This can aid in determining the most effective way to treat infections [ 36 ].

Whole-genome sequencing

A potent technique for the diagnosis of infectious disorders is WGS. This technique entails sequencing every piece of DNA found in a sample of microorganisms, which can produce a thorough examination of every bacterium present. It allows for the high-resolution characterization of bacterial pathogens in terms of traits including pathogenicity, molecular epidemiology, and antibiotic resistance [ 37 ]. When infectious disease outbreaks occur, whole-genome sequencing can be very helpful in locating the outbreak's origin and monitoring the disease's progress [ 38 , 39 ]. The identification of bacterial strains resistant to antibiotics is another application of WGS. This method involves identifying specific genes that confer antibiotic resistance, which can aid in determining the most effective way to treat infections [ 40 ]. The development of next-generation sequencing equipment has decreased the cost of WGS. However, the absence of a WGS beginner's protocol still prevents its acceptance in some contexts [ 37 ].

In bioinformatics and data analysis, molecular and genomic approaches and numerous data sets are produced by molecular and genomic techniques, and these data sets need to be evaluated and understood. Medical microbiology uses molecular and genomic techniques, while bioinformatics is the branch of science that deals with the processing and interpretation of biological data [ 41 , 42 ]. In bioinformatics, biological data are analyzed and interpreted using computational tools and algorithms. The identification of certain genes and proteins, sequence comparison, and biological molecule structure and function predictions are all possible with the use of these technologies. For the processing and interpretation of the enormous volumes of data produced by molecular and genomic techniques, bioinformatics is crucial [ 43 ].

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry

The 1980s saw the development of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) by Hillenkamp and Karas, which is essential for analyzing biomolecule masses. It ionizes molecules using a matrix and laser to create distinctive profiles for proteomics, biomolecule analysis, and microbiological identification. Their laser-ionization and time-of-flight detection methods are used in clinical diagnostics, drug development, and quality control because they provide quick, precise molecular insights. It quickly rose to prominence in clinical microbiology, revolutionizing the identification of microorganisms based on mass spectra, "fingerprints," and proteomics, detecting and characterizing proteins [ 44 ]. It evolved, advancing sample processing, instrument design, and data analysis for use in a variety of industries, including environmental analysis, food safety, and drug discovery. Due to its great sensitivity, speed, and versatility, MALDI-TOF has become a cornerstone of mass spectrometry and is essential to modern research across many fields of science [ 45 ].

Next-generation sequencing

The field of genetic research has been completely changed by NGS, also known as massively parallel or deep sequencing. This technology makes it possible to quickly and affordably sequence complete genomes, opening the door for ground-breaking research in a variety of domains. Next-generation sequencing has ushered in a new era of genomics research by making it possible to sequence the human genome in just one day, enabling improvements in personalized medicine, evolutionary biology, microbiology, and other fields. This review examines the foundations, uses, and consequences of NGS, emphasizing its contribution to advancing knowledge and its potential to alter how we perceive the genetic universe [ 46 ]. Next-generation sequencing has revolutionized genomics. After a modest start in 1977 with Sanger sequencing, NGS developed in the 2000s, characterized by 454's pyro-sequencing and Illumina's parallel technology [ 47 ]. Ion Torrent's semiconductor detection, Pac Bio's real-time readings, and Oxford Nanopore's nanopore-based sequencing have all contributed to the advancement of NGS. This revolution affected genetics, medicine, agriculture, and other fields through initiatives like the Human Genome Project. Genomic profiling, cancer detection, infectious disease detection, transcriptome analysis, epigenetic, non-invasive prenatal testing (NIPT), pharmacogenomics, diagnosis of rare diseases, microbiome research, and human leukocyte antigen (HLA) typing are a few of the uses of NGS. Next-generation sequencing has issues with data handling yet continues to advance molecular diagnostics and tailored treatment while providing speed, accuracy, and scalability.

Challenges in implementing molecular and genomic approaches

Although molecular and genomic approaches have several benefits over conventional diagnostic methods, there are also several practical obstacles [ 48 ]. Some medical facilities might not have the necessary tools and knowledge that these methods demand. Additionally, these methods might be pricey, which might restrict who can use them [ 49 ]. Numerous data sets are produced by molecular and genomic techniques, and these data sets need to be evaluated and understood. This calls for specific knowledge in data processing and bioinformatics, which might not be available in all medical facilities [ 50 ]. The use of molecular and genomic methods in medical microbiology has ethical and legal implications. Concerns including patient privacy, informed consent, and the ownership and usage of genetic data are among them [ 51 ].

Future of molecular and genomic approaches

Molecular and genomic methods are anticipated to influence the direction of medical microbiology in the future. With these methods, infectious illness diagnoses can be made more quickly and precisely, which can lead to better patient outcomes [ 52 , 53 ]. Additionally, in light of the increasing prevalence of antibiotic resistance, molecular and genomic techniques can be used to discover bacterial strains that are resistant to antibiotics [ 54 ].

Future developments are projected to increase the accessibility and availability of molecular and genomic methods. It will be necessary to do this by creating new technology and educating medical personnel on how to use it [ 55 ]. Additionally, continued investigation into the ethical and legal issues connected to the application of molecular and genomic techniques in medical microbiology will be necessary [ 56 ].

Conclusions

Medical microbiology is undergoing a revolution thanks to molecular and genomic techniques. Infectious disease diagnoses can now be made more quickly and precisely thanks to these methods, which can benefit patient outcomes. Additionally, molecular and genomic techniques can aid in the identification of bacterial strains that are resistant to antibiotics, which is becoming more crucial in light of the rise in antibiotic resistance. Molecular and genomic techniques are likely to be made more broadly available and accessible in the future, notwithstanding the difficulties involved in their implementation. This will necessitate continual study and development as well as instruction in the usage of these methods for medical practitioners. In the end, the application of molecular and genomic methods in medical microbiology can revolutionize how we identify and treat infectious diseases while also enhancing patient outcomes globally.

The authors have declared that no competing interests exist.

Genetic Engineering - Essay Samples And Topic Ideas For Free

Genetic engineering, the deliberate manipulation of an organism’s genetic material to achieve desired traits, has revolutionized medicine, agriculture, and various other fields. Essays on genetic engineering could delve into its techniques, applications, and the ethical considerations surrounding its use. Discussions might also cover the societal and environmental impact of genetic engineering, exploring topics like genetically modified organisms (GMOs), gene therapy, and CRISPR technology. Additionally, analyzing the potential future advancements in genetic engineering, the regulatory frameworks governing its use, and the public perception and discourse regarding genetic engineering can provide a well-rounded understanding of this groundbreaking yet controversial technological domain. We have collected a large number of free essay examples about Genetic Engineering you can find at PapersOwl Website. You can use our samples for inspiration to write your own essay, research paper, or just to explore a new topic for yourself.

Genetic Engineering in Medicine

Every person is born with flaws, whether it be on a small or large scale. If there were a way to fix these imperfections before birth, how would this affect the human race? To some people, it may seem almost foreign and unrealistic to think about a world where a parent can “design” their future child. However, in a few decades, it won't be so strange to hear that people are genetically modifying their children. Bioethicist Ronald Green of Dartmouth […]

The Discovery of Boyer and Cohen in Genetic Engineering

More than likely, everyone has heard a teenager describe what they want their first born to look like exactly. From sex to eye color, they have it all planned out. Years after that, they soon realize they have no control over how their child will look. Until recently, genetics was a thing of chance and parents had no control over what set of genes a child would get from their parent. Genetic engineering has been an idea since early 12,000 […]

GMO Position Paper

Abstract GMO foods are a controversial subject today. In this paper I will discuss some of pros of GMOs, thoughts for the future, personal opinions as well as other subjects concerning genetically modified foods and my research on the subject. GMO Position Paper What is the definition of Genetically Modified Foods? According to the World Health Organization (WHO) Genetically Modified Foods are foods produced from or using GM organisms (WHO, 2017). The issue of GMOs in food has become prevalent […]

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GMO Foods are Killing Us

According to the Grocery Manufacturers Association, GMOs are ubiquitous in the food supply--present in about 80 percent of processed foods in the United States of America (Linden 1). People use genetic modification to improve the quality and quantity of foods. In Gandhi’s explanation of The Seven Deadly Social Sins, he explains how Science without humanity is when scientists or people in general, develop new technologies without taking into consideration of what they may do to humans. In this case, they […]

The Positive and Negative Effects of GMO’s

According to Dictionary.com, a genetically modified organism (GMO), is an organism or microorganism whose genetic material has been modified by means of genetic engineering. They take an organism and inject it with genetics it doesn't usually produce to enhance its abilities. Genetically modified organisms are typically used for crop production of maize, canola, and cotton. Like anything else in the world, GMO's have a positive and negative effect our changing society. Positive Impact of GMO Genetically modified organisms may also […]

Are G.M.O. Foods Safe?

Following the discovery of the double helix, DNA structure in 1953, genetic engineering became increasingly popular in experimenting with different genetic traits, within different organisms. The science behind Genetically Modified Organisms (GMOs) is different from selective breeding. It involves the insertion of DNA from one organism into another, or a modification of an organism's DNA in order to achieve a desired trait. Today, scientist and farmers have teamed up in producing GMO's with animals and plants that have affected today's […]

GMO’s and World Hunger

As the world begins to feel the constraints of overpopulation and diminishing resources, the rate at which people are affected by chronic world hunger continues to grow exponentially (Geldof). Record climate change brought about by global warming and an increase in greenhouse emissions has increased the longevity of droughts, causing the desert to spread, and what small area of forest we have to left to soon run out (Gerry). According to research conducted at Harvard, the world population is estimated […]

GMO Food Labeling

Genetically modified organisms, also known as GMO, are organisms that have been genetically altered to have a specific characteristic or trait. GMOs were first introduced in 1994 and no one knew about the potential health problems that could come. Nowadays more Americans worry about where their food comes from. Even though GMOs can help starvation and save labor costs, GMOs should be labeled because we don't know the long-term health effects, and GM foods can cause a numerous amount of […]

Pro GMO: Feeding the World

To fully understand the benefits GMO's we should first be able to define it. According to source, GMO's in reference to agriculture is, a plant and or microorganism whose genetic makeup has been modified in a laboratory using genetic engineering or transgenic technology.  GMO's are not a newly introduced subject, in fact we have been eating GMO's for hundreds of years and we are still perfectly healthy. The public that is opposed to the use and of GMO crops, often […]

Social and Ethical Implications of GMO’s

There are biotechnology debates about genetically modified organisms in society and can be illustrated with the serious conflict between two groups that are voicing possible benefits and possible drawbacks to GMOs. First, are the Agricultural biotech companies that provide tools to farmers to yield bigger better crops but in the most cost-effective way, also known as Agri-biotech. Agri-biotech investors and their affiliated scientists versus the independent scientists, environmentalists, farmers, and consumers (Maghari 1). On one hand, you have the Agri-biotech […]

GMO Labeling

GMO's Food is a crucial and fundamental necessity of human life. Because of this, the United States had an average of 2.08 million farms in 2014 (Facts, 2018). Production from these farms not only play a factor within the U.S. but globally as well. Mexico, Canada, and China are just some of the countries that received agricultural products from the United States in 2015 that added up to a total of $133 billion dollars (Facts, 2018). Such success of exports […]

GMO’s Foundation of Life

Imagine eating chemicals instead of food. Not so tasty I would imagine. With GMOs, you may actually be eating chemicals. GMO is an acronym for Genetically Modified Organisms, or organism that have undergone changes in a lab. Some of these changes may include heat resistance, frost resistance, resistance to pesticides, etc¦ Because of GMOs harmful traits and inconclusive research, GMOs should be banned. Surprisingly, we have been genetically modifying organisms for over 30,000 years. Selective breeding, where humans encourage two […]

GMO the Biological Weapon

I really believe that people don't have to eat healthy; they just have to know what they are eating, and then they'll each better. That is really the movement we are behind (Musk)Do we really know what we eat? Does people know what GMO is, and how harmful they are for us? The truth is most of us does not read the tiny shrift on the labels. We buy products based on the marketing. Furthermore, we are constantly being used […]

Research Paper: Genetically Modified Organisms

Genetically modified organisms, otherwise referred to as GMOs, is a highly debated and researched topic throughout the world, however, highly prevalent in the United States today. It is plant, animals, or other organism in which their genetic makeup has been altered or modified by either genetic engineering or transgenic technology. GMOs are used either in the medical field or agriculturally, looking to cure diseases and create vaccines or attempt to get the healthiest or highest profit out a product. Prior […]

GMO’s: Feeding the World or Killing it

Many people today are often amazed by the amount of food and nutrients created a year for human consumption. The constant prominence of genetically modified (GMO) foods is not only intimidating, but confusing. The dictionary definition of GMO is genetically modified organism: an organism or microorganism whose genetic material has been altered by means of genetic engineering. Simply explained, foods are plants and animals that have had their genetic makeup artificially altered by scientists to make them grow faster, taste […]

Genetically Modified Plants

Genetically Modified Organisms, better known as GMO's, are plants or animals whose gene code has been altered using genetic information from other living organisms such as bacteria, other plant species, animals, and even humans. Typically, genetic modification of plants involves the addition of genetic sequences coding for specific proteins that result in a desirable heritable trait. These proteins alter the biology of the plant to enhance characteristics that are beneficial to humans. But along with altered or added genes for […]

What are GMOs?

A GMO, a genetically modified organism, is an organism that has had its characteristics changed through the modification of its DNA. By changing an organism's genome, scientists can change its characteristics, appearance, or even capability. Scientists can create GMOs by deleting or altering sections of an organism's DNA through lab techniques of gene splicing or gene insertion. Removal of an existing gene from an organism is known as gene splicing, where adding an artificial gene to an organism is known […]

GMO’s at a Corporate Scale

Genetic modification is the direct alteration of an organism's genetic material using biotechnology. Currently, this form of genetic modification is a rapidly developing field because of the benefits it provides the environment and mankind. However, with GMOs on the rise a great deal of controversy has been sparked. While GMOs prove to be beneficial in some cases, they do have they're drawbacks. All around the world people are beginning to protest against GMOs and the giant corporations which develop them. […]

GMO in Foods

Genetically modified organisms (GMOs) is a reasonably well-known concept. This experimental technology modifies DNA from different species, including plants, animals, and bacteria, to create a longer lasting food product. Many people are not aware of the adverse side effects GMOs can cause to the body ("What are GMOs?"). Although it might be a solution to creating an abundance of food production, GMOs are harmful to the environment and increases the risk of health problems on the consumers (Baetens). The purpose […]

GMO’s on Developing Countries

Biotechnology advanced in 1973 when Stanley Cohen and Professor Herbert Boyer originated Deoxyribonucleic Acid (DNA) recombination (Friedberg, 590). Recombinant DNA (rDNA), more commonly known as 'transgenic' or genetically modified organisms, are made by withdrawing genes from one species and forcefully infusing the genes into another species. According to Catherine Feuillet (2015), GMOs were created with objectives to improve crop characteristics and overall help the environment. Not only are seeds being manipulated, but animals are too. Although the animals are mainly […]

Environmental Science GMFS: our Savior or Destroyer

GMFs are genetically modified foods created by Herbert Boyer and Stanley Cohen back in 1973. This technological advance led to more genetically modified foods and organisms being created and manufactured. GMFs are created either by direct genetic code modification or selective breeding. Direct genetic code modification occurs when a certain part of the genetic code is cut out, copied into bacteria, made into bullets, loaded into a gene gun, and shot into a cell where the genetic information incorporates itself […]

GMOs: a Solution to Global Hunger and Malnutrition?

It is common knowledge that a nutritious well-balanced diet is important to our health and well-being. Some of the time food biotechnology prompts resistance from buyer gatherings and hostile to biotechnology from lobbyist gatherings. As far as safety for humans, it is commonly recognized that testing of GMO (Genetically Modified Organisms) foods have been deficient in the identification of unpredicted allergens or poisons which can prompt destructive outcomes. However, research has shown that GMOs may be extremely useful in a […]

Climate Change and Genetically Modified Food

Social issues are the factors that affect how human beings live. One of the most prominent social issues in the twenty first century is climate change and genetically modified food. The two issues are somewhat related since climate change has changed weather patterns, forcing human beings to change their farming methods one way to adapt to climate change has been genetically modified food. Both climate change and genetically modified food have subject to rigorous debate and there lacks consensus regarding […]

Study on Improving the Calculation Accuracy of Sphygmomanometer Based on Bidirectional Filtering

Abstract: Objective: In the current market, there are all kinds of blood pressure monitors that use different filtering algorithms. Therefore, their calculation accuracy varies. Through research, it's determined that the calculation accuracy of a sphygmomanometer's filtering algorithm can be effectively improved. This is proven via experimental data obtained from the processing of various filter algorithms. A comparison of this data with the gains from the bidirectional filter algorithm shows that the bidirectional filter algorithm improves the calculation accuracy of the […]

GMO’s Educating the other Point of View

These risks are associated with a product that has been modified from its original state and is made up of different components that may be harmful to those that are sensitive to those to components. It is important that producers make the new allergy risks and different components from the original state are noticeable whether it is printed on the label, advertised on the tv or radio or if an article is published about it. It needs to be made […]

Should we Grow and Eat GMO’s

In 1986, the first tests for genetically modified tobacco crops were conducted in Belgium (History). Since then, the process has become much more widespread, and today, genetically modified foods are commonplace across the globe. For example, in 2016, Brazil had almost 50 million hectares of genetically modified crops; Argentina had 23 million, and India had 10 million (Acreage). As of 2017, a massive 89% of corn in the United States was grown with genetically modified seeds (Recent Trends). The term, […]

Karyotypes: a Key to Genetic Analysis

Ever heard of a karyotype? It's like a secret snapshot of your genetic playbook, showing how your chromosomes line up. Chromosomes are the DNA-packed structures inside your cells that hold all the instructions for how you grow and function. This karyotype thing? It's the key that scientists and doctors use to peek into the mysteries of genetics, from spotting disorders to digging into our evolutionary story. Imagine a karyotype as a cool picture or digital map of all your chromosomes, […]

Genetic Engineering and Destiny: Insights from ‘Gattaca’

In the annals of science fiction cinema, few films have sparked as much intellectual debate as Andrew Niccol's 1997 masterpiece, "Gattaca". This film isn't just a narrative journey; it's a philosophical exploration of bioethics, identity, and the human spirit in the face of a genetically predetermined society. Through the lens of its protagonist, Vincent, "Gattaca" delves into themes of genetic engineering, determinism, and the undying human quest for belonging and achievement. Set in a not-too-distant future where genetic manipulation determines […]

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