Microbes in Human Welfare Class 12 Notes Biology Chapter 10 - CBSE

Chapter:10

What are Microbes in Human Welfare?

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Microbes

Microbes are the most adaptable creatures that can be found everywhere from air, soil, water to even deep inside geysers, deep in soil, under snow and even in acidic medium.

Use Of Microbes In Household Products

Lactic acid bacteria (LAB)

$$\text{Milk} \xrightarrow{\text{LAB}}\text{Curd}$$

Cheese Making

The bacterium Propionibacterium sharmanii is used in ‘Swiss cheese’ to give it its characteristic holes by producing large amount of carbon dioxide (CO₂).

Fermentation

Dough is fermented by bacteria, which produces CO₂ gas.
Dough is used for making breads which is fermented by baker’s yeast (Saccharomyces cerevisiae).

Industrial Applications

Fermented Beverages

Saccharomyces cerevisiae (brewer’s yeast:) is used for production of wine, beer, whisky, brandy, rum, etc.

Antibiotics

The bacterium Propionibacterium sharmanii is used in ‘Swiss cheese’ to give it its characteristic holes by producing large amount of carbon dioxide (CO₂).

Production of Chemicals and Bioactive Agents

Production of Enzymes

Microbes In Production Of Biogas

Anaerobic bacteria during secondary treatment usually produces methane along with CO2 and H2. Such bacteria are called methanogens. Example - Methanobacterium
Methanogens are commonly found in anaerobic sludge (as in sewage treatment) and in the rumen of cattles.

Microbes as Bio Control Agents

➥ Bacillus thuringiensis (Bt) is used to control butterfly caterpillars.
➥ Trichoderma (fungus) living in roots of plants acts as a bio control agent against several plant pathogens.
➥ Baculoviruses, specially Nucleopolyhedrovirus, are used as narrow spectrum insecticidal agents.

Bio control agents are particularly useful when useful insects are required to be conserved under IPM (integrated pest management programmes).

Microbes In Sewage Treatment

Bio-fertilizers are organisms that enrich the nutrient quality of the soil.
Many bacteria, fungi, and cyanobacteria act as bio fertilizers.
Glomus (fungi) also form symbiotic association with plants (Mycorrhiza). It absorbs phosphorus and pass it to plants.
Cyanobacteria such as Nostoc, Anabaena, etc. also fix atmospheric nitrogen and act as bio-fertilizers especially in paddy fields.