Chapter 10. Microbes In Human Welfare

Microbes In Household Products

* Lactobacillus, also known as lactic acid bacteria (LAB), helps make curd
from milk.
* Microbes help in curing of tea, cheese and tobacco.
* Different varieties of cheese are distinguished by their characteristic texture, flavour and taste, all of which depend on he choice of microbe used.
* Microbes also help in the making of food items like bread, idli-dosa, dhokla and khaman.
* Several traditional drinks such as toddy are prepared by fermentation due to microbes.
* Microbes are also used to ferment fish, soyabean and bamboo shoots to prepare different foods.

Microbes In Industrial Products


* Saccharomyces cervisiae, also known as brewer’s yeast, ferments
different malted cereals and fruit juices to produce ethanol.
* Other than alcoholic beverages, microbes help in the industrial production of antibiotics, chemicals, enzymes and other such bioactive molecules.
* Microbes also produce chemicals such as organic acids and enzymes.
* Bacteria and fungi are also used in microbiological cultures, where they are grown on nutritive solutions and allowed to colonise so that they can be studied.

Microbes In Sewage Products


* Microbes are naturally present in sewage and every day, gallons of waste
water are treated inside a sewage plant.
* * Microbial treatment of sewage takes place in two stages: primary and secondary treatment.
* In the primary stage of sewage treatment, the objective is to remove coarse solids in sewage by filtration and sedimentation.
* The secondary stage of sewage treatment aims to reduce organic matter in the effluents. It reduces the BOD or biochemical oxygen demand of water.
* During the second stage of secondary stage of secondary treatment, anaerobic bacteria digest bacteria and fungi present in the activated
sludge and produce a mixture of gases known as biogas.
* The effluents that remain from the secondary treatment plant are now released into natural water bodies like rivers and streams.

Microbes In Production of Biogas


* Different microbes produce different gases depending on the organic
substrates they utilise.
* Anaerobic bacteria that produce copious amounts of methane along with carbon dioxide and hydrogen gases are known as methanogens.
* Biogas or gobar gas is produced by microbial activity inside a biogas plant.
* In India, the technology to produce biogas was developed by the Indian Agricultural Research Institute (IARI) and the Khadi and Village Industries Commission (KVIC).

Microbes As Biocontrol Agents


* The use of biological methods such as natural predators to control plant
diseases and pests is called biocontrol.
* The beneficial organisms nurtured to deal with pests are known as biocontrol agents.
* In organic farming, insects and pests are not always eradicated. They are kept at manageable levels within the living ecosystem.
* Beneficial insects are conserved under an Integrated Pest Management(IPM) programme.
* Bt stands for bacteria Bacillus thuringiensis. It is a microbial biocontrol agent that is introduced into fields to control butterfly caterpillars.
* Pyrehtrum, an insecticide extracted from the chrysanthemum cinerariifolium, is also used in biocontrol methods.
* The free-living fungus, Trichoderma, and baculoviruses also act as biocontrol agents.

Microbes As Bio fertilisers


* Bio fertilisers are organisms such as bacteria, fungi and cyanobacteria
that enrich the nutrient quality of the soil.
* In organic farming, bio fertilisers are used instead of chemical fertilisers that pollute both environment and soil.
* Rhizobium bacteria exist symbiotically in the root nodules of leguminous plants, where it converts atmospheric nitrogen into usable, organic forms for plant use.
* Cyanobacteria such as Anabaena, Nostoc and Oscilliatoria are also known to fix atmospheric nitrogen in special cells called heterocysts.
* Fungi too form symbiotic associations like mycorrhiza. They absorb phosphorous from the soil and provide it to plants for nutrition.

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