Industrial microbiology and GMOs
Bacteria as factories.
Bioreactors / fermenters. Stainless steel vessels (1 L–100 000 L) in which microbes grow under controlled conditions:
- Sterilisation — heat-sterilised before inoculation; aseptic technique throughout.
- Temperature — water jacket maintains optimum (e.g. 37 °C for E. coli).
- pH — sensors + acid/base addition.
- Aeration / stirring — supplies O₂ and prevents settling.
- Nutrient feed — substrate (sugar, ammonia) added.
Batch culture: all nutrients added at the start; product harvested at the end. Simple but limited yield.
Continuous culture: nutrients added and culture removed continuously; sustains exponential growth. Used in some industrial processes.
Example: industrial insulin production. GM E. coli carrying the human insulin gene grown in massive fermenters. Insulin extracted and purified. Cheaper and safer than historical pig pancreas extraction.
GM crops.
- Bt crops carry a Bacillus thuringiensis toxin gene → kills target pests → less pesticide.
- Golden rice carries genes for β-carotene biosynthesis → tackles vitamin A deficiency.
- Herbicide-resistant crops (e.g. Roundup-Ready) survive herbicide treatment → simpler weed control.
Knock-out mice. Gene targeting disables specific genes — used to study gene function (e.g. obesity research).
Bioremediation. Microbes used to clean pollutants:
- Oil spills — bacteria break down hydrocarbons (helped by nutrient addition).
- Heavy metals — some bacteria sequester or detoxify lead, mercury.
- Sewage treatment — bacterial digestion of organic matter.
- Bioreactors: controlled fermenters for microbial products.
- GM bacteria, plants, animals each have applications.
- Bioremediation cleans pollutants biologically.