Introduction –

• Micro are the major components of biological systems on this earth.
• Microbes are present everywhere that is in soil, water, air, inside, the body of plants and animals inside thermal vents, deep in the soil, the layers of snow several meters thick and in highly acidic environments.
• Microbes are diverse such that they are protozoa, bacteria, fungi and microscopic plants viruses, viroids and prions that are proteinaceous infectious agents.
• Microbes like bacteria and many fungi can be grown on nutritive media to form colonies which can be seen with naked eyes.
• Microbes cause a large number of diseases in human beings, animals and plants but microbes are not harmful. Several microbes are useful to man in diverse ways.

Production of curd –

• Milk is converted to curd by micro-organisms such as lactobacillus and others commonly called lactic acid bacteria (LAB) which grow in milk and convert it to curd.
• During growth of bacteria, the LAB produce acids that coagulate and digest the milk proteins.
• A small amount of curd added to the fresh milk as inoculum or starter which at suitable temperatures multiphy, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin B12.
• In our stomach, the LAB play very beneficial role in checking diseases causing microbes.

Production of dough –

• The dough, which is used for making foods such as dosa and idli, is also fermented by bacteria.
• The puffed-up appearance of dough is due to the production or CO2
• The dough, which is used for making bread, is fermented using baker’s yeast
  ( Saccharomyces cerevisiae ).
• A number of traditional drinks and foods are made by fermentation by the microbes.
• Toddy, a traditional drink of some parts of southern India is made by fermenting sap from palms.
• Microbes are also used to ferment fish, soya bean and bamboo shoots to make foods.

Production of toddy –

• It is a traditional drink of southern india.
• It is made by fermentation of sap from palm trees by bacteria.

Production of cheese –

• Different varieties of cheese are known by their characteristic texture, flavor and taste, the specificity coming from the microbes used.
• The large holes in ‘swiss cheese’ are due to production of a large amount of CO2 by a bacterium named propionibacterium shermanii.
• The ‘ Roquefort cheese’ are ripened by growing a specific on them, which gives them a particular flavor.

Microbes in industrial products –

• Production on an industrial scale, requires microbes in very large vessels called fermenters.
• Beverages antibiotics enzymes are some of the industrial products produced by microbes.

Fermented beverages –

• Microbes are used for the production of beverages like wine, beer, whiskey brandy or rum.
• Saccharomyces cerevisiae , is used for the production of fermented beverages.
• Malted cereals and fruit juices are fermented by S. cerevisiae to produce ethanol.
• Wine and beer are produced without distillation.
• Whisky, brandy and rum are produced by distillation of the fermented broth.

Antibiotics –

• Antibiotics are the chemical substances which are produced by some microbes and can kill or stop the growth of other microbes.
• Alexander Fleming discovered penicillin obtained from penicillium notatum which was the first antibiotic to be discovered.
• Alexander Fleming while working on staphylococci bacteria observed a mould growing in one of his unwashed culture plates around which staphylococci could not grow and he found out that it was due to a chemical produced by penicillium notatum.
• Antibiotics are used against the deadly diseases like plague, whooping cough, leprosy, malaria etc.

Chemicals, enzymes and other bioactive molecules –

Microbes are used for the production of organic acids, alcohols and enzymes.

Examples :-
Aspergillus niger (a fungus )is the producer of citric acid.
Acetobacter aceti (a bacterium)produces acetic acid.
Clostridium butylicyum (a bacterium) is the producer of butyric acid and lactobacillus (a bacterium).
Yeast ( saccharomyces cerevisiae ) is used for commercial production of ethanol.
Lactobacillus (a bacterium) is the producer of lactic acid.

Enzymes produced by the microbes are :-

1. Lipases – used in detergent formulations.
2. Pectinases and proteases- used in making bottled fruit juices clearer.

Streptokinase produced by the bacterium streptococcus is used as a ‘ clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infarction leading to heart attack.

Bioactive molecules produced by microbes are :-

Cyclosporin A –

Used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus trichoderma polysporum.

Statins –

Produced by the yeast monascus purpureus is used as blood-cholesterol lowering agents which acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol.