Here are several types of industrial processes where microorga­nisms are used to produce desirable end products which have well defined industrial uses and applications. These may be broadly classi­fied into the following groups.

1. Foods and food additives. Microorganisms themselves are cultivated on a large scale for use as food and animal feed. Yeast, fungi, and algae are produced from media containing inorganic nitrogen source and other readily available and cheap nutrients. Such food products are good sources of protein,, vitamins, and other organic nutrients. In recent years microbial processes are employed for large scale production of amino acids.

2. Alcoholic beverages. Fruit juices and extract of grains are fermented   with the   production of   beer,   wine,   and other alcoholic beverages.

3.  Manufacture of various chemicals. Microorganisms fer­ment various substances,   usually carbohydrates,   in nutrient   media. They produce a variety   of chemicals   (various alcohols, lactic acid, acetic acid, citric acid, gluconic acid, etc.)   which are being recovered, purified and sold.

4. Therapeutic compounds.  Antibiotics, vitamins, and ster­oid drugs are prominent in this category.

5. Industrial enzymes.  A number of microbial,enzymes have industrial applications, and are produced on a large scale