In Industrial Microbiology, microbes are used to synthesise a number of products valuable to human beings. This Industry has provided products that have profoundly changed our lives and life spans. These products include beverages, food additives, products for human and animal health, and biofuels.
Microbes especially yeast have been used from time immemorial for the production of beverages like Wine, Beer, Whisky, Brandy or Rum. For this purpose, the yeast Saccharomyces cerevisiae (commonly called Brewer’s yeast) is used for fermenting malted cereals and fruit juices to produce ethanol.
Among these beverages, Wine and Beer are produced without distillation whereas whisky, brandy and rum are distilled beverages.
Antibiotics produced by microbes are regarded was one of the most significant discoveries of the twentieth century and have made major contributions towards the welfare of human society.
Many antibiotics are produced by microorganisms, predominantly by Actinomycetes in the genus Streptomycin (e.g. Tetracycline, Streptomycin, Actinomycin D) and by filamentous fungi (e.g. Penicillin, Cephalosporin).
3. Organic acids:
Microbes are also used for the commercial and industrial production of certain organic acids. These compounds can be produced directly from glucose (e.g. gluconic acid) or formed as end products from pyruvate or ethanol.
4. Amino Acids:
Amino acids such as Lysine and Glutamic acid are used in the food industry as nutritional supplements in bread products and as flavour enhancing compounds such as Monosodium Glutamate (MSG).
In early days, monosodium glutamate (MSG) was extracted from the vegetable proteins (wheat and soy).
Amino acids are generally synthesised as primary metabolites by microbes. However, when the rate and amount of synthesis of some amino acids exceed the cell’s need for protein synthesis, then cell excrete them into the surrounding medium.
Many microbes synthesise and excrete large quantities of enzymes into the surrounding medium. Using this feature of these tiny organisms, many enzymes have been produced commercially. These include Amylase, Cellulase, Protease, Lipase, Pectinase, Streptokinase and many others.
Enzymes are extensively used in food processing and preservation, washing powders, Leather Industry, Paper Industry and in scientific research.
Vitamins are some organic compounds which are capable of performing many life-sustaining functions inside our body. These compounds cannot be synthesised by humans, and therefore, they have to be supplied in small amounts in the diet.
Microbes are capable of synthesizing these compounds and hence they can be used for the commercial production of many of the Vitamins e.g. thiamine (Vitamin B1), riboflavin (Vitamin B2), pyridoxine (Vitamin B6), folic acid, pantothenic acid (Vitamin B5), biotin (Vitamin B7), Vitamin B12, ascorbic acid (Vitamin C).
Organic solvents such as ethanol, acetone, butanol and glycerol are some very important chemicals that are widely used in petrochemical industries. These chemicals can be commercially produced by using microbes and low-cost raw materials (e.g. wood, cellulose, starch).
Brazil was the first country to produce ethanol in large scale by yeast fermentation, utilising sugarcane and cassava.
Yeast (Saccharomyces cerevisiae) is used for commercial production of ethanol. This alcohol is used as motor fuel and is often referred to as green petrol.
8. Single Cell Protein (SCP):
Single Cell Protein (SCP) can serve as an alternate source of energy when a larger portion of the world is suffering from hunger and malnutrition. SCPs are microbial cells that are rich in protein, minerals, fats, carbohydrate and vitamins and can be used as food supplements for humans and animals.
Microbes like Spirulina can be grown easily on materials like waste water from potato processing plants (containing starch), straw, molasses, animal manure and even sewage, to produce large quantities.
Steroids are a very important group of chemicals, which are used as anti-inflammatory drugs, and as hormones such as estrogens and progesterone, which are used in oral contraceptives.
Producing steroids from animal sources or chemically systhesising them is difficult, but microorganisms can synthesise steroids from sterols or from related compounds.
Vaccines are a product of Industrial Microbiology. Many antiviral vaccines are mass-produced in chicken eggs or cell cultures.
The production of vaccines against bacterial diseases usually requires the growth of large amounts of the bacteria. Recombinant DNA technology is increasingly important in the development and production of subunit vaccines.
11. Pharmaceutical Drugs:
Many pharmaceutical drugs are also produced by microbes e.g. Cyclosporin A, that is used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus Trichoderma polysporum.
Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol-lowering agents. It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.