Brief Survey of Microbes as Friends and Foes, Biology tutorial


Microorganisms take place in large numbers of most natural environments and bring about numerous changes. A few are desirable and others are undesirable. Microorganisms influence the well being of people in numerous ways. Most of them are beneficial to man and can be termed 'friends' whereas some are injurious and can be regarded as 'foes' to man. The beneficial impact of microorganisms ranges from the production of goods and pharmaceutical products, to the improvement of soil fertility, environmental cleanup whereas their harmful result can be seen in their capability to cause disease in animals, man and plants and also their usage in the biological warfare. Though, there are many species of microorganisms which carry out friendly and valuable functions than those that harm the other living organisms.

Microorganisms as Friends:

Microorganisms have found application in a variety of facets of life. They are helpful in food industries to manufacture many food substances, in medicine to generate antibiotics and vaccines, in environmental protection and in agriculture, to optimize yield.

Microorganisms and Food Production:

1) Most of the microorganisms are utilized to produce many of the foods and beverages we use. Microbial-produced food products contain properties that are much dissimilar from those of the starting materials. Most of such food products are produced by the fermentation.

2) Fermentation is the chemical conversion of organic compounds taken out by microorganisms and their enzymes. In industrial fermentation, raw materials (that is, substrate) are transformed by microorganisms in a controlled favorable environment to form a desired end product substance.

3) The accumulation of fermentation products like ethanol and lactic acid generates feature flavors and other desirable properties in the food substances.

4) Pickles and some sausages are as well produced through fermentation methods.

5) Microorganisms are employed to produce fermented dairy products like cheese, yoghurt and acidophilus milk.

6) They are as well employed to produce alcoholic beverages such as beer through conversion of sugar to alcohol and carbon-dioxide.

Production of Pharmaceuticals:

Microorganisms are employed to produce different pharmaceuticals like steroids, antibiotics, vitamins, hormones and so on. Antibiotics are microbial produced substances synthetically derived from the natural sources which inhibit or kill microorganisms; Steroids regulate different features of human metabolisms and are generated by organisms like Rhizopus nigricans.

Vaccines are produced utilizing microorganisms by the antigenic properties to draw out a primary immune response; they are employed to prevent many once deadly diseases like small pox, polio, measles, tuberculosis, diphtheria and whooping cough.


Vitamins are necessary animal nutritional factors; a few vitamins are produced by microbial fermentation, example: Vitamin B12 by Streptomyces, B12 by Pseudomonas denitrificans and Propionibacterium shermanni. Riboflavin generated through different species of Clostridium and Ashbya gossypii.

Human growth hormone and human insulin are produced through genetically engineered bacteria.

Production of Organic Acids:

A variety of organic acids are produced through microorganisms. Illustrations are:

1) Gluconic acid: It is employed as a pharmaceutical to supply calcium to the body by some fungi comprising Penicillium and Aspergillus species. Citric acid is produced through Aspergillus niger and employed as a food additive especially in the production of soft-drinks.

2) Gibberellic acid: It is a plant hormone which is made by the fungus Gibberella fujikuroi. It is employed as growth promoting substances to stimulate the plant growth flowering and seed germination.

3) Lactic acid through various lactic acid bacteria for illustration: Lactobacillus delbrueckii, lactic is utilized in foods as preservatives, in leather production for deliming hides and in the textile industry for the treatment of fabric and in plastics making in baking powders.

Energy Production:

Microorganisms play main roles in the energy production. Microbes are employed in fermentation to produce ethanol and in biogas reactions to generate methane by utilizing different forms of agricultural and urban wastes.

Microbial production of synthetic fuels acts as alternative fuel resources to the petroleum.

The microbial manufacture of ethanol from sugarcane or cornstarch has become a significant source of a valuable fuel, specifically in regions of the world which have plentiful supplies of plant residues like Brazil and is becoming famous in the United States.

The bacteria Zymomonas mobilis and Thermoanaerobacter ethanolicus and various yeast strains are employed for the product of ethanol.

Methane (that is, natural gas) is produced by methanogenic bacteria is the other significant natural renewable energy sources.

Methane can be employed for the generation of mechanical, electrical and heat energy.

Microorganisms and Agriculture:

1) Agriculture depends in numerous ways on the actions of microorganisms. Microorganisms assist in nitrogen fixation employed by plants for growth.

2) In terrestrial habitats, the microbial fixation of the atmospheric nitrogen is taken out by free living bacteria like Rhizobium and Bradyrhizobium living in the symbiotic relationship with plants.

3) Legumes live in close relation by the bacteria which form structures termed as nodules on their roots.

4) These bacteria in the root nodules of the legumes, transform atmospheric N2 fixed into Nitrogen (NH3) those plants make use of for the growth and removes the requirement for chemical fertilizers.

Sewage Treatment:

Microorganisms are as well employed in the sewage treatment. Especially cultured microbes are employed in the biological treatment of sewage and industrial waste effluent in a procedure termed as bioaugmentation. These microbes assist to get rid of waste materials which could encompass accumulated in the environment.

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