1) Decay and decomposition

Soil bacteria are important to us because they cause decomposition of the organic matter. By this, harmful wastes are removed and when disintegrated, the organic matters serve as the nutrient of the plants.

The dead bodies and organic wastes liberated by the organisms (both of plants and animals) are decomposed by saprophytic bacteria. The decomposition of carbohydrates is caused by bacteria even in the absence of oxygen.

The process is called fermentation. Also, decomposition of proteinaceous materials is done by bacteria by the process of putrefaction. The amino acids thus, liberated, are utilized by the plant world as nutrient.

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2) Enhancing Soil Fertility

Some bacteria maintain the soil fertility and others enhance it. The fertility of the soil is proportional to the nitrogen content. Nitrogen is an important ingredient in the structure and function of the living beings.

Yet excepting certain bacteria, no living organism can fix nitrogen although nearly four fifths (80%) of the atmosphere contain nitrogen. This work is done by ammonifying, nitrifying and nitrogen fixing bacteria.

Ammonifying bacteria break amino acids that constitute proteins. Nitrifying bacteria bring it to nitrate form which can be assimilated by the plants from the soil.

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Nitrogen fixing bacteria like Azotobacter, Clostridium live free in the soil and fix atmospheric nitrogen. Rhizobium like bacteria live symbiotically with root systems of leguminous plants and fix from the atmosphere nitrogen.

3) Bacteria in industry

Man has utilized the services of bacteria for various industrial purposes. The diary industry solely depends on bacteria. Souring and curdling of milk is done by lactic acid bacteria (Lactobacillus).

Through the process of lactic acid fermentation, the disaccharide of lactose sugar that constitutes the carbohydrate component of milk is converted to lactic acid and carbon dioxide. The acid causes the souring and thereby, the milk protein coagulates.

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Oxidation of alcohol to vinegar (acetic acid) is done by certain bacteria. The curing of tea, tobacco and indigo are other economically beneficial effect of bacteria. The processes of tanning hides in leather industry, manufacture of sponges also involve use of bacteria.

The production of jute and linen is done by bacterial activity. The retting bacteria loosen the fibers when the plants are submerged in water and thereby help extraction of fibers which are used for making clothes, ropes etc.

The cocoa beans are white colored and quite bitter in taste. The bacteria digest the bitter coverings of the seeds and give it the characteristic color, flavor and aroma.

Saprophytic bacteria. The decomposition of carbohydrates is caused by bacteria even in the absence of oxygen. The process is called fermentation. Also, decomposition of proteinaceous materials is done by bacteria by the process of putrefaction. The amino acids thus, liberated, are utilized by the plant world as nutrient.

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2) Enhancing Soil Fertility

Some bacteria maintain the soil fertility and others enhance it. The fertility of the soil is proportional to the nitrogen content. Nitrogen is an important ingredient in the structure and function of the living beings.

Yet excepting certain bacteria, no living organism can fix nitrogen although nearly four fifths (8o %) of the atmosphere contain nitrogen. This work is done by ammonifying, nitrifying and nitrogen fixing bacteria. Ammonifying bacteria break amino acids that constitute proteins. Nitrifying bacteria bring it to nitrate form which can be assimilated by the plants from the soil.

Nitrogen fixing bacteria like Azotobacter, Clostridium live free in the soil and fix atmospheric nitrogen. Rhizobium like bacteria lives symbiotically with root systems of leguminous plants and fix from the atmosphere nitrogen.

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3) Bacteria in industry

Man has utilized the services of bacteria for various industrial purposes. The diary industry solely depends on bacteria. Souring and curdling of milk is done by lactic acid bacteria (Lactobacillus).

Through the process of lactic acid fermentation, the disaccharide of lactose sugar that constitutes the carbohydrate component of milk is converted to lactic acid and carbon dioxide. The acid causes the souring and thereby, the milk protein coagulates.

The Oxidation of alcohol to vinegar (acetic acid) is done by certain bacteria. The curing of tea, tobacco and indigo are other economically beneficial effect of bacteria. The processes of tanning hides in leather industry, manufacture of sponges also involve use of bacteria.

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The production of jute and linen is done by bacterial activity. The retting Bacteria loosen the fibers when the plants are submerged in water and thereby help extraction of fibers which are used for making clothes, ropes etc.

The cocoa beans are white colored and quite bitter in taste. The bacteria digest the bitter coverings of the seeds and give it the characteristic color, flavor and aroma.

Flavor to the beverages, sweets and food materials. Vitamins produced from bacteria have nutritive value.

4) Bacteria in medicine

(a) As antibiotics

Antibiotics arc prepared from secretions of microorganisms which are selectively toxic. First antibiotic extracted from a bacterium was streptomycin by Walksman in 1941 (Penicillin was however, the first antibiotic to be discovered from a fungus, Penicillium notatum by Fleming in 1929). It was obtained from Streptomycin. Now- a-days, a number of bacterial antibiotics are available.

(b) Serums and Vaccines

These are substances obtained from bacteria to develop immunity to various diseases. Serums are used against the diseases like diphtheria, pneumonia etc and vaccines are used against cholera, typhoid etc.

5) Bacteria in genetic engineering and biotechnology

Plasmids that occur in bacteria are important tools in the modern field of biological science called biotechnology. Genes obtained from the bacteria are transferred and incorporated in other living organisms to develop their disease resistance, productivity, quality etc. A number of genetically modified crops have been developed using bacteria. Ex-Bt-cotton developed from Bacillus thuringensis.