RESEARCH STARTER

Genetically modified bacteria

Genetically modified bacteria are microorganisms that have been altered through genetic engineering techniques to incorporate DNA from other organisms. This process began with key discoveries in the mid-20th century, including the demonstration of gene transfer among bacteria and the development of restriction enzymes, which allow scientists to cut and splice DNA from various sources. These modified bacteria often utilize plasmids—small, circular DNA molecules that can carry genes of interest, such as those for antibiotic resistance or the production of human proteins like insulin.

One notable application of genetically modified bacteria is in medicine, where bacteria like Escherichia coli have been engineered to produce human insulin, providing a reliable and less allergenic alternative to animal-sourced insulin. Additionally, genetically modified bacteria are used as vectors to introduce genes into plants, enhancing traits like pest resistance. The bacterium Agrobacterium tumefaciens, for example, has been instrumental in integrating new genetic material into plant cells.

While the use of genetically modified organisms has sparked public debate regarding environmental and health implications, regulatory frameworks have evolved to facilitate their development and application. By 2002, numerous permits for field tests of genetically altered plants and microorganisms had been issued, highlighting the growing acceptance and integration of biotechnology in agriculture and medicine.

Full Article

  • Categories: Bacteria; biotechnology; economic botany and plant uses; genetics

The ability to genetically engineer bacteria is the outcome of several independent discoveries. In 1944, Oswald Avery and his coworkers demonstrated gene transfer among bacteria using purified DNA (deoxyribonucleic acid), a process called transformation. In the 1960s, the discovery of restriction enzymes helped make recombinant DNA technology possible. Such enzymes cut DNA molecules at specific sites, allowing fragments from different sources to be joined into the same DNA molecule.

Restriction enzymes cut DNA at specific recognition sites and can be used on DNA from many different organisms. DNA from any source that contains the same recognition sequence will be cut in the same way by a given restriction enzyme. The treated DNA molecules are allowed to bind with one another, while a second set of enzymes called ligases are used to fuse the fragments together. The recombinant molecules may then be introduced into bacterial cells through transformation. In this manner, the cell acquires whatever genetic information is found in the DNA. Descendants of the transformed cells will be genetically identical, forming clones of the original. Scientists also use CRISPR-Cas systems (clustered regularly interspaced short palindromic repeats) to make precise changes in bacterial DNA.

Bacterial Plasmids

The most common forms of genetically modified DNA are bacterial plasmids, small circular molecules separate from the cell chromosome. Plasmids may be altered to serve as appropriate vectors (carriers of genetic material) for genetic engineering, usually containing an antibiotic resistance gene for selection of only those cells that have incorporated the DNA. Once the cell has incorporated the plasmid, it acquires the ability to produce any gene product encoded on the molecule.

One of the first genetically modified bacteria used for medical purposes, Escherichia coli, produced human insulin, which became an approved medical product in the United States in 1982. Prior to the creation of the insulin-producing bacterium, diabetics were dependent upon insulin purified from animals. In addition to being relatively expensive, insulin obtained from animals produced allergic reactions in some individuals. Insulin obtained from genetically modified bacteria is identical to human insulin. Subsequent experiments also engineered bacteria able to produce a variety of human proteins, including human growth hormone, interferon, and granulocyte colony-stimulating factor.

Use in Plants

Genetically modified bacteria may also serve as vectors for the introduction of genes into plants. The bacterium Agrobacterium tumefaciens, the cause of the plant disease called crown gall, contains a plasmid called Ti. Following infection of the plant cell by the bacterium, the plasmid is integrated into the host chromosome, becoming part of the plant’s genetic material. Any genes that were part of the plasmid are integrated as well. Desired genes can be introduced into the plasmid, promoting pest or disease resistance.

In April 1987, scientists in California sprayed strawberry plants with genetically altered ice-minus Pseudomonas syringae bacteria to improve the plants’ freeze resistance, marking the first deliberate release of genetically altered organisms in the United States to be sanctioned by the Environmental Protection Agency (EPA). The release of the bacteria climaxed more than a decade of public debate over what would happen when the first products of biotechnology became commercially available. Fears centered on the creation of bacteria that might radically alter the environment through the elaboration of gene products not normally found in such cells. Some feared that so-called superbacteria might be created with unusual resistance to conventional medical treatment. Despite these concerns, approval for further releases of genetically altered bacteria soon followed, and the restrictions on release were greatly relaxed. By 2002, permits for field tests of hundreds of genetically altered plants and microorganisms had been granted. Genetically modified bacteria are also used in industry and environmental research, including enzyme production, biosensors, and the breakdown of some pollutants. Engineered bacteria are also studied in synthetic biology for new metabolic pathways, sustainable manufacturing, microbiome-based treatments, and targeted cancer therapies.


Bibliography

Ballister, Edward R., et al. “The Emerging Landscape of Engineered Bacteria Cancer Therapies.” Nature Biotechnology, vol. 43, no. 5, 2025, pp. 672–6, doi:10.1038/s41587-025-02623-x. Accessed 5 Apr. 2026.

Dale, Jeremy W. Molecular Genetics of Bacteria. 3rd ed., John Wiley, 1998.

“EPA Approves First Use in Environment of Genetically Altered Bacteria.” US Environmental Protection Agency, 14 Nov. 1985, www.epa.gov/archive/epa/aboutepa/epa-approves-first-use-environment-genetically-altered-bacteria.html. Accessed 5 Apr. 2026.

"Genetically Modified Bacteria Break Down Plastics in Saltwater." US National Science Foundation, 26 Apr. 2023, www.nsf.gov/news/genetically-modified-bacteria-break-down-plastics. Accessed 5 Apr. 2026.

Griffiths, Anthony J. F., et al. “Recombinant DNA.” Encyclopedia Britannica, 9 Mar. 2026, www.britannica.com/science/recombinant-DNA-technology. Accessed 5 Apr. 2026.

Levin, Morris A., editor. Engineered Organisms in Environmental Settings: Biotechnological and Agricultural Applications. CRC Press, 1996.

Miesfeld, Roger L. Applied Molecular Genetics. John Wiley, 1999.

Moon, Tae Seok. “Probiotic and Microbiota Engineering for Practical Applications.” Current Opinion in Food Science, vol. 56, Apr. 2024, article 101130, doi:10.1016/j.cofs.2024.101130. Accessed 5 Apr. 2026.

Riggs, Arthur D. “Making, Cloning, and the Expression of Human Insulin Genes in Bacteria: The Path to Humulin.” Endocrine Reviews, vol. 42, no. 3, June 2021, pp. 374–80, doi:10.1210/endrev/bnaa029. Accessed 5 Apr. 2026.

"Scientists Discover How Engineered Bacteria Supercharge the Immune System to Kill Cancer." SciTechDaily, 3 Mar. 2025, scitechdaily.com/scientists-discover-how-engineered-bacteria-supercharge-the-immune-system-to-kill-cancer/. Accessed 5 Apr. 2026.

“Scientists Engineer Living DNA Sensors.” National Institute of Biomedical Imaging and Bioengineering, 5 July 2023, www.nibib.nih.gov/news-events/newsroom/scientists-engineer-living-dna-sensors. Accessed 5 Apr. 2026.

Scown, Corinne D., and Jay D. Keasling. “Sustainable Manufacturing with Synthetic Biology.” Nature Biotechnology, vol. 40, 2022, pp. 304–7, doi:10.1038/s41587-022-01248-8. Accessed 5 Apr. 2026.

Smith, Kimberly. “What is CRISPR?” Biomedical Beat, National Institute of General Medical Sciences, 16 Oct. 2024, www.nigms.nih.gov/biobeat/2024/10/what-is-crispr. Accessed 5 Apr. 2026.

Song, Peng, et al. “Microbial Proteases and Their Applications.” Frontiers in Microbiology, vol. 14, 14 Sept. 2023, article 1236368, doi:10.3389/fmicb.2023.1236368. Accessed 5 Apr. 2026.

“Synthetic Biology.” National Institute of Biomedical Imaging and Bioengineering, Sept. 2025, www.nibib.nih.gov/science-education/science-topics/synthetic-biology. Accessed 5 Apr. 2026.

Wozniak, Carol A., et al. “Regulation of Genetically Engineered Microorganisms under FIFRA, FFDCA, and TSCA.” Regulation of Agricultural Biotechnology: The United States and Canada, 1 Jan. 2012, pp. 57–94, doi:10.1007/978-94-007-2156-2_4. Accessed 5 Apr. 2026.

Full Article

  • Categories: Bacteria; biotechnology; economic botany and plant uses; genetics

The ability to genetically engineer bacteria is the outcome of several independent discoveries. In 1944, Oswald Avery and his coworkers demonstrated gene transfer among bacteria using purified DNA (deoxyribonucleic acid), a process called transformation. In the 1960s, the discovery of restriction enzymes helped make recombinant DNA technology possible. Such enzymes cut DNA molecules at specific sites, allowing fragments from different sources to be joined into the same DNA molecule.

Restriction enzymes cut DNA at specific recognition sites and can be used on DNA from many different organisms. DNA from any source that contains the same recognition sequence will be cut in the same way by a given restriction enzyme. The treated DNA molecules are allowed to bind with one another, while a second set of enzymes called ligases are used to fuse the fragments together. The recombinant molecules may then be introduced into bacterial cells through transformation. In this manner, the cell acquires whatever genetic information is found in the DNA. Descendants of the transformed cells will be genetically identical, forming clones of the original. Scientists also use CRISPR-Cas systems (clustered regularly interspaced short palindromic repeats) to make precise changes in bacterial DNA.

Bacterial Plasmids

The most common forms of genetically modified DNA are bacterial plasmids, small circular molecules separate from the cell chromosome. Plasmids may be altered to serve as appropriate vectors (carriers of genetic material) for genetic engineering, usually containing an antibiotic resistance gene for selection of only those cells that have incorporated the DNA. Once the cell has incorporated the plasmid, it acquires the ability to produce any gene product encoded on the molecule.

One of the first genetically modified bacteria used for medical purposes, Escherichia coli, produced human insulin, which became an approved medical product in the United States in 1982. Prior to the creation of the insulin-producing bacterium, diabetics were dependent upon insulin purified from animals. In addition to being relatively expensive, insulin obtained from animals produced allergic reactions in some individuals. Insulin obtained from genetically modified bacteria is identical to human insulin. Subsequent experiments also engineered bacteria able to produce a variety of human proteins, including human growth hormone, interferon, and granulocyte colony-stimulating factor.

Use in Plants

Genetically modified bacteria may also serve as vectors for the introduction of genes into plants. The bacterium Agrobacterium tumefaciens, the cause of the plant disease called crown gall, contains a plasmid called Ti. Following infection of the plant cell by the bacterium, the plasmid is integrated into the host chromosome, becoming part of the plant’s genetic material. Any genes that were part of the plasmid are integrated as well. Desired genes can be introduced into the plasmid, promoting pest or disease resistance.

In April 1987, scientists in California sprayed strawberry plants with genetically altered ice-minus Pseudomonas syringae bacteria to improve the plants’ freeze resistance, marking the first deliberate release of genetically altered organisms in the United States to be sanctioned by the Environmental Protection Agency (EPA). The release of the bacteria climaxed more than a decade of public debate over what would happen when the first products of biotechnology became commercially available. Fears centered on the creation of bacteria that might radically alter the environment through the elaboration of gene products not normally found in such cells. Some feared that so-called superbacteria might be created with unusual resistance to conventional medical treatment. Despite these concerns, approval for further releases of genetically altered bacteria soon followed, and the restrictions on release were greatly relaxed. By 2002, permits for field tests of hundreds of genetically altered plants and microorganisms had been granted. Genetically modified bacteria are also used in industry and environmental research, including enzyme production, biosensors, and the breakdown of some pollutants. Engineered bacteria are also studied in synthetic biology for new metabolic pathways, sustainable manufacturing, microbiome-based treatments, and targeted cancer therapies.


Bibliography

Ballister, Edward R., et al. “The Emerging Landscape of Engineered Bacteria Cancer Therapies.” Nature Biotechnology, vol. 43, no. 5, 2025, pp. 672–6, doi:10.1038/s41587-025-02623-x. Accessed 5 Apr. 2026.

Dale, Jeremy W. Molecular Genetics of Bacteria. 3rd ed., John Wiley, 1998.

“EPA Approves First Use in Environment of Genetically Altered Bacteria.” US Environmental Protection Agency, 14 Nov. 1985, www.epa.gov/archive/epa/aboutepa/epa-approves-first-use-environment-genetically-altered-bacteria.html. Accessed 5 Apr. 2026.

"Genetically Modified Bacteria Break Down Plastics in Saltwater." US National Science Foundation, 26 Apr. 2023, www.nsf.gov/news/genetically-modified-bacteria-break-down-plastics. Accessed 5 Apr. 2026.

Griffiths, Anthony J. F., et al. “Recombinant DNA.” Encyclopedia Britannica, 9 Mar. 2026, www.britannica.com/science/recombinant-DNA-technology. Accessed 5 Apr. 2026.

Levin, Morris A., editor. Engineered Organisms in Environmental Settings: Biotechnological and Agricultural Applications. CRC Press, 1996.

Miesfeld, Roger L. Applied Molecular Genetics. John Wiley, 1999.

Moon, Tae Seok. “Probiotic and Microbiota Engineering for Practical Applications.” Current Opinion in Food Science, vol. 56, Apr. 2024, article 101130, doi:10.1016/j.cofs.2024.101130. Accessed 5 Apr. 2026.

Riggs, Arthur D. “Making, Cloning, and the Expression of Human Insulin Genes in Bacteria: The Path to Humulin.” Endocrine Reviews, vol. 42, no. 3, June 2021, pp. 374–80, doi:10.1210/endrev/bnaa029. Accessed 5 Apr. 2026.

"Scientists Discover How Engineered Bacteria Supercharge the Immune System to Kill Cancer." SciTechDaily, 3 Mar. 2025, scitechdaily.com/scientists-discover-how-engineered-bacteria-supercharge-the-immune-system-to-kill-cancer/. Accessed 5 Apr. 2026.

“Scientists Engineer Living DNA Sensors.” National Institute of Biomedical Imaging and Bioengineering, 5 July 2023, www.nibib.nih.gov/news-events/newsroom/scientists-engineer-living-dna-sensors. Accessed 5 Apr. 2026.

Scown, Corinne D., and Jay D. Keasling. “Sustainable Manufacturing with Synthetic Biology.” Nature Biotechnology, vol. 40, 2022, pp. 304–7, doi:10.1038/s41587-022-01248-8. Accessed 5 Apr. 2026.

Smith, Kimberly. “What is CRISPR?” Biomedical Beat, National Institute of General Medical Sciences, 16 Oct. 2024, www.nigms.nih.gov/biobeat/2024/10/what-is-crispr. Accessed 5 Apr. 2026.

Song, Peng, et al. “Microbial Proteases and Their Applications.” Frontiers in Microbiology, vol. 14, 14 Sept. 2023, article 1236368, doi:10.3389/fmicb.2023.1236368. Accessed 5 Apr. 2026.

“Synthetic Biology.” National Institute of Biomedical Imaging and Bioengineering, Sept. 2025, www.nibib.nih.gov/science-education/science-topics/synthetic-biology. Accessed 5 Apr. 2026.

Wozniak, Carol A., et al. “Regulation of Genetically Engineered Microorganisms under FIFRA, FFDCA, and TSCA.” Regulation of Agricultural Biotechnology: The United States and Canada, 1 Jan. 2012, pp. 57–94, doi:10.1007/978-94-007-2156-2_4. Accessed 5 Apr. 2026.

More Like ThisRelated Articles

Related Articles (4)

Related Articles (4)