Since the time immemorial microorganisms have been used for production of various products. After the development of pure cultures, improved strains of various routes of metabolism they are exploited for various useful industrial and biotech products which have never been possible by ordinary strains.
Can you imagine, E. coli re producing human insulin? Exploitation of microorganisms for some of the useful products are given in and discussed below:
(a) Exploitation of Whole Cells of Microorganisms:
Since vedic period, whole cells of microorganisms have been used for production of products as starter culture. For example, a spoonful one day old curd is mixed with boiled and cool down (about 37°C) two litre milk to produce curd and cheese. Similarly, jalebi is also produced after mixing yeast cells with wheat flour (called maida) preparation.
Whole cells of Candida utilis, Torula sp. and Spirulina maxima are now used as single cell protein (SCP). SCPs are the good source of protein. For example, S. maxima contains about 60% protein.
Vaccines for typhoid, tetanus and tuberculosis have also been prepared by using whole cells of respective bacteria.
Tempeh is one of the oriental fungal food of Indonesia, Japan and other countries. It is produced by inoculating soaked and de-hulled soybean cotyledons with Rhizopus oligosporus and incubating for 4-5 days.
Biofertilizers have also been produced industrially in India and other countries and commercialised with different trade names. Pure cultures of bacteria such as species of Rhizobium or Pseudomonas are mixed with carriers (inert organic waste), dried and packed in polythene and sold in marker.
The National Biofertiliser Development Centre (NBDC), Ministry of Agriculture (Ghaziabad, U.P) has been established to promote the scientists to make available the know-how to the farmers.
Many industries have been established that have been preparing biofertilizers and selling to the market. The farmers must use biofertilizers for eco-friendly sustainable enhanced crop production.
(b) Production of Primary Metabolites:
Primary metabolites (alcohols, acids, vitamins, etc.) are such microbial products that are produced during exponential growth phase (log phase). These are used by microorganisms e.g. ethanol, citric acid, vitamin C, vitamin B12, etc.
(c) Biomining (Bioleaching) and Bioremediation:
The microbes are exploited for extraction of certain metals like gold, silver, copper, sulphur, iron, etc. Through metabolic reactions microbes precipitate the respective metal in the solution.
For example, Thiobacillus ferooxidans precipitates iron from the ores. Similarly, the most contaminant of soil are chlorinated solvents, hydrocarbons, poly- chlorobiphenyls and metals.
Now-a-days, microbial preparations are used for degradation of these pollutants. The waste organic materials treated with selected potential strains of microorganisms are rendered into less- or nontoxic forms. This process of remedying pollution is called bioremediation.
(d) Production of Recombinant Proteins:
After 1980, recombinant DNA technology has given much hope for production of novel proteins using genetically engineered microorganisms. Human insulin is the first therapeutic protein produced by genetically engineered E. coli. Similarly, transformed yeast cells have been used to produce transformed hepatitis vaccine. For detail see Chapter 3.