Genetically modified bacteria

Genetically modified bacteria were the first organisms to be modified in the laboratory, due to their simple genetics.^[1] These organisms are now used for several purposes, and are particularly important in producing large amounts of pure human proteins for use in medicine.^[2]

The first example of this occurred in 1978 when Herbert Boyer working at a University of California laboratory took a version of the human insulin gene and inserted into the bacterium Escherichia coli to produce synthetic "human" insulin.

The drug industry has made good use of this discovery in its quest to produce medication for diabetes.^[3] Similar bacteria have been used to produce clotting factors to treat haemophilia,^[4] and human growth hormone to treat various forms of dwarfism.^[5][6] These recombinant proteins are safer than the products they replaced, since the older products were purified from cadavers and could transmit diseases.^[7] Indeed the human-derived proteins caused many cases of AIDS and hepatitis C in haemophilliacs and Creutzfeldt-Jakob disease from human growth hormone.^[7][8]

For instance, the bacteria which cause tooth decay are called Streptococcus mutans. These bacteria consume leftover sugars in the mouth, producing lactic acid that corrodes tooth enamel and ultimately causes cavities. Scientists have recently modified Streptococcus mutans to produce no lactic acid.^[9] These transgenic bacteria, if properly colonized in a person's mouth, could reduce the formation of cavities.^[10] Transgenic microbes have also been used in recent research to kill or hinder tumors, and to fight Crohn's disease^[11] Genetically modified bacteria are also used in some soils to facilitate crop growth, and can also produce chemicals which are toxic to crop pests.

Bacteria-synthesized transgenic products

• Insulin
• Hepatitis hej B vaccine
• Tissue plasminogen activator
• Human growth hormone
• Ice-minus bacteria
• Interferon

Further reading

• Karl Drlica Understanding DNA and Gene Cloning: A Guide for the Curious, 4th Edition ISBN 978-0-471-43416-0.

References

1. ^ Melo, Eduardo O.; Canavessi, Aurea M. O.; Franco, Mauricio M.; Rumpf, Rodolpho (2007). "Animal transgenesis: state of the art and applications". J. Appl. Genet. 48 (1): 47–61. doi:10.1007/BF03194657. PMID 17272861. Archived from the original on 26 September 2009. http://www.webcitation.org/5k5aYeGAs. 
2. ^ Leader, Benjamin; Baca, Qentin J.; Golan, David E. (January 2008). "Protein therapeutics: a summary and pharmacological classification". Nat Rev Drug Discov. A guide to drug discovery 7 (1): 21–39. doi:10.1038/nrd2399. PMID 18097458. 
   Leader 2008 — Fee required for access to full text.
3. ^ Walsh, Gary (April 2005). "Therapeutic insulins and their large-scale manufacture". Appl. Microbiol. Biotechnol. 67 (2): 151–159. doi:10.1007/s00253-004-1809-x. PMID 15580495. 
   Walsh 2005 — Fee required for access to full text.
4. ^ Pipe, Steven W. (May 2008). "Recombinant clotting factors". Thromb. Haemost. 99 (5): 840–850. doi:10.1160/TH07-10-0593. PMID 18449413. 
5. ^ Bryant, Jackie; Baxter, Louise; Cave, Carolyn B.; Milne, Ruairidh (2007). "Recombinant growth hormone for idiopathic short stature in children and adolescents". Cochrane Database Syst Rev (3): CD004440. doi:10.1002/14651858.CD004440.pub2. PMID 17636758. 
   Bryant 2007 — Fee required for access to full text.
6. ^ Baxter L, Bryant J, Cave CB, Milne R (2007). "Recombinant growth hormone for children and adolescents with Turner syndrome". Cochrane Database Syst Rev (1): CD003887. doi:10.1002/14651858.CD003887.pub2. PMID 17253498. 
7. ^ ^{a b} Foster PR (October 2000). "Prions and blood products". Ann. Med. 32 (7): 501–13. PMID 11087171. 
8. ^ Key NS, Negrier C (August 2007). "Coagulation factor concentrates: past, present, and future". Lancet 370 (9585): 439–48. doi:10.1016/S0140-6736(07)61199-4. PMID 17679021. 
9. ^ Hillman JD (August 2002). "Genetically modified Streptococcus mutans for the prevention of dental caries". Antonie Van Leeuwenhoek 82 (1-4): 361–6. doi:10.1023/A:1020695902160. PMID 12369203. 
10. ^ Hillman JD, Mo J, McDonell E, Cvitkovitch D, Hillman CH (May 2007). "Modification of an effector strain for replacement therapy of dental caries to enable clinical safety trials". J. Appl. Microbiol. 102 (5): 1209–19. doi:10.1111/j.1365-2672.2007.03316.x. PMID 17448156. 
11. ^ Braat, H (June 2006). "A phase I trial with transgenic bacteria expressing interleukin-10 in Crohn's disease". Clinical Gastroenterology and Hepatology 4: 754–9. doi:10.1016/j.cgh.2006.03.028. PMID 16716759.