Genetically Modified Microbes

When thinking of genetically modified organisms (GMOs), plants and animals are probably the first to come to mind, which overlooks possibly the most important group of all: GM microorganisms, or microbes. It was in the 1970s that the first GMO was made – it was bacteria (specifically E. coli). A few years later, researchers were churning out GM bacteria that produced useful human proteins, such as insulin and blood clotting factors (important for people with diabetes and hemophilia, respectively).

Today, a wide variety of drugs, hormones, and other products have been created in microbes for the medical market. This include erythropoietin (which regulates red blood cell production), interferons (which stimulate the immune system), vaccines (e.g., against the Hepatitis B virus), human growth hormone (hGH), and many more. Most recently in the medical field, GM bacteria are in clinical trials that may prevent cavities, and other bacteria are being created that may possibly block HIV infection.

Many of the food additives we consume today on a daily basis are also made by GM microbes. To name just a few, the list includes vitamins (B2, C), amino acids that improve flavors (e.g., aspartame), food additives (e.g., xanthan), food preservatives (e.g., nisin), enzymes used in food during specific chemical reactions (e.g., making cheese, breads, certain alcohols, and some sugars), and many more.

Since the 1980s, GM bacteria have even been purposefully released into the environment, after approval by the U.S. Environmental Protection Agency (EPA). In 1985, researchers took bacteria that normally encourage ice formation on plants, and got rid of a gene that they needed to do this. Consequently, plants with the modified bacteria don’t form frost until around 23°F, saving the plants from damages brought upon by an early frost, or unusually cold weather. Soon after that, researchers made and released bacteria that were even better at nitrogen-fixation to help legume plants (like beans, lentils, peanuts, soy, and more). Bacteria have even been made to clean up the environment – some have been modified to break down a compound related to TNT. Ongoing work is being done to see how long the bacteria persist in the soil (often they’re undetectable after a few weeks or a year, but sometimes they persist for more than two years based on some studies) to address any complications from releasing them, such as interactions with the “normal” bacteria and other organisms.

Recently, even more fascinating and useful bacteria have been made, such as bacteria that make arsenic detection kits possible, bacteria that can break down hazardous chemicals like mercury, and bacteria that can make stronger, lighter-weight silk. (Move over silkworms, you’ve got a new competitor – bacteria!)

So next time you think of GMOs, don’t forget that some amazing little microbes belong to this group, and they continue to help us make incredible scientific, and medical, accomplishments.

(And if you want to read more about genetic modifications, or gene therapies, that have been done with people, check out the earlier post “What Has Gene Therapy Done For You Lately?”)

For further reading:

• Teisha J. Rowland’s book Biology Bytes: Digestible Essays on Stem Cells and Modern Medicine
• Gary Walsh’s article “Therapeutic insulins and their large-scale manufacture”
• Steven W. Pipe’s article “Recombinant clotting factors”
• Mareike Viebahn, Eric Smit, Debora C.M. Glandorf, Karel Wernars, and Peter A.H.M. Bakker’s article “Effect of Genetically Modified Bacteria on Ecosystems and Their Potential Benefits for Bioremediation and Biocontrol of Plant Diseases – A Review”
• Katherine Bourzac’s article “Making Spider-Strength Materials”
• Katherine Sanderson’s article “New Portable Kit Detects Arsenic in Wells”
• Oscar N. Ruiz, Derry Alvarez, Gloriene Gonzalez-Ruiz, and Cesar Torres’ article “Characterization of mercury bioremediation by transgenic bacteria expressing metallothionein and polyphosphate kinase”