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Classification of Microbes

Household Applications

  • Lactic acid bacteria (LAB)

    • Milk Curd

    • LAB produces acids that coagulate and partially digest milk proteins.

    • Small amount of curd that is added to the milk for curdling acts as an inoculum containing thousands of LABS, which further multiply.

    • LAB enhances the nutritional value of milk by increasing Vitamin B12.

    • LAB present in stomach prevents infections.

  • Fermentation
    • ​Dosa and idli dough is fermented by bacteria, which produces CO2 gas and gives it a puffed-up appearance.
    • ​Dough used for making breads is fermented by baker’s yeast (Saccharomyces cerevisiae).
    • ​‘Toddy’, a traditional drink from South India is made by fermenting sap from palm trees.
    • The xanthan gum, which is used in thickening of ice creams, puddings, chocolates etc. is obtained by fermentation of starch and molasses. The fermentation is carried out with the help of Xanthomonas sp. Xanthum gum is also used in the production of pigments, fertilizers, weedicides, textile pigments, tooth pastes, high quality paper, etc.

Industrial applications
  • For industrial purposes, microbes are grown in large vessels called fermentors.

  • On industrial scale, fermented beverages, antibiotics, enzymes, and other bioactive molecules are prepared using microbes.

  • Fermented beverages 
    Saccharomyces cerevisiae, also called brewer’s yeast, is used to prepare wine, beer, whisky, brandy, rum, etc. depending upon the type of raw material and processing.

  • If fermented broth is distilled, then brandy and rum are produced while wine and beer are produced without distillation.

  • Antibiotics

    • Certain microorganisms inhibit the growth of other microorganisms wherever they grow.

    • Antibiotics are chemical substances produced by certain microbes that kill or retard the growth of other microbes (disease-causing microbes).

    • Penicillin discovered by Alexander Fleming was the first antibiotic to be discovered.

    • Fleming discovered it by chance when he was working on the bacterium Staphylococcus. He discovered that growth of Staphylococcus ceases in the culture plates where Penicillium notatum was grown.

    • Later on, its use as an effective antibiotic was established by Chain and Florey.

  • Chemicals, enzymes, and bioactive agents


Substance produced

Fungus Aspergillus niger

Citric acid

Bacterium Acetobacter aceti

Acetic acid

Bacterium Clostridium butylicum

Butyric acid

Bacterium Lactobacillus 

Lactic acid

Yeast S.cerevisiae


Bacterium Streptococcus

Streptokinase (used as a clot buster for removing clots from blood vessels of patients with myocardial infarction)

Fungus Trichoderma polysporum

Cyclosporin A (used as immune-suppressive agent in organ transplantation)

Yeast Monascus purpureus

Statins (lower blood cholesterol levels)

  • Leather industry
Bacteria are also used in leather industries during tanning of leather. The soft, perishable parts of the skin (hide) are degraded with the help of certain bacteria.

Do you know which organisms are classified as microorganisms? Let us find out.

  • Microorganisms can be classified into four major groups depending on their characteristics. Let us study the major groups of microorganisms.

There is a lot of variety of microorganisms in nature. The five major groups are as follows:

1. Bacteria

2. Fungi

3. Protozoa

4. Algae

5. Viruses


Bacteria are the most abundant organisms on earth. They are found everywhere − on land, in water, and in the air. T…

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