Microbes in Industrial Production

Industrial-Scale Fermentation

Household fermentation relies on whatever conditions happen to be present in a kitchen. Industrial microbial production, by contrast, takes place in purpose-built vessels called fermenters or bioreactors, where temperature, pH, oxygen supply, nutrient concentration and the specific microbial strain used can all be precisely controlled and optimised, allowing valuable microbial products to be manufactured reliably and at very large scale.

Organic Acids

Several organic acids used across the food, pharmaceutical and chemical industries are produced industrially using microorganisms rather than by chemical synthesis, since microbial routes are often cheaper and more sustainable at scale.

• Citric acid, widely used as an acidulant and preservative in foods, beverages and pharmaceuticals, is produced industrially by growing the fungus Aspergillus niger on a sugar-rich growth medium (commonly molasses); the fungus excretes large quantities of citric acid as a metabolic by-product, which is then purified.
• Lactic acid, used similarly as a food-industry acidulant and preservative (and in some biodegradable-plastic manufacture), is produced using the bacterium Lactobacillus grown industrially, in a scaled-up version of the same fermentation used to make curd.
• Butyric acid, another industrial organic acid, is produced by the anaerobic bacterium Clostridium butylicum.

Alcohols and Enzymes

Ethanol for industrial use -- including fuel-grade ethanol -- is produced at large scale by fermenting sugar sources with the yeast Saccharomyces cerevisiae, following the same underlying fermentation chemistry that produces beverage alcohol, but optimised for maximum ethanol yield rather than flavour.

Microbes are also major industrial sources of enzymes, which are used to speed up specific chemical reactions in manufacturing:

• Lipases, produced by various microorganisms, are used in detergent formulations, where they help break down fatty stains, and are added directly to some laundry detergents.
• Pectinases, produced by fungi, are used in the fruit-juice industry to clarify juices by breaking down pectin, the substance that otherwise keeps juice cloudy.
• Streptokinase, produced by the bacterium Streptococcus, is modified and used medically as a "clot buster" -- an enzyme injected into patients following a heart attack to dissolve blood clots blocking the coronary arteries.

Other Bioactive Molecules

Certain microorganisms are industrially cultivated specifically to produce complex bioactive pharmaceutical compounds that would be difficult or prohibitively expensive to synthesise chemically:

• Cyclosporin A, an immunosuppressive drug used to prevent organ rejection following transplant surgery, is produced by the fungus Trichoderma polysporum. …