Microbes in Human Welfare shows how useful microorganisms are harnessed across daily life and industry, from making curd, bread and fermented foods at home to producing alcoholic beverages, antibiotics, organic acids and enzymes in large fermentors. It also covers their role in sewage treatment, biogas production, biocontrol of pests and diseases, and biofertilisers that enrich the soil. This applied, fact-heavy chapter is a reliable NEET scorer because most questions test which specific microbe gives which product.
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Microbes Are Mostly Helpful
Most microbes are tiny chemical workers we put to work, not villains causing disease.
Same chemistry at home and in giant industrial fermentors (bioreactors).
- They serve us in food, medicine, sewage, fuel, farming
- Choose the microbe whose ‘waste’ product you want
- Whole chapter = humans harnessing microbial by-products
Microbes in Household Products
Curd, dough and bread are all set by microbes fermenting milk or batter.
Curd = bacterium; bread = yeast. Never swap them.
- LAB raise vitamin B12 and check gut pathogens
- Dough/idli/dosa puff up due to CO2 (not methane)
- Bread leavened by baker’s yeast Saccharomyces cerevisiae
Toddy & Cheese
Traditional fermented foods each have a signature microbe NEET loves to test.
Toddy = fermented palm SAP, not barley or grapes.
- Roquefort cheese ripened/flavoured by fungus Penicillium roqueforti
- Cheese is one of the oldest microbe-made foods
- Swiss holes = bacterium; Roquefort flavour = fungus
Fermented Beverages
Brewer’s yeast turns malted cereals and fruit juice into ethanol.
Wine & beer = WITHOUT distillation; whisky/brandy/rum = BY distillation.
- Distillation concentrates the alcohol
- Same yeast as bread, different end product wanted
- Grown in large fermentors (bioreactors) at scale
Antibiotics & Bioactive Molecules
Microbes make chemicals that kill other microbes or act as drugs.
Chain & Florey proved its full clinical value; saved WWII soldiers.
- Cyclosporin A (Trichoderma polysporum) = immunosuppressant for transplants
- Statins (Monascus purpureus) = lower blood cholesterol
- Streptokinase (Streptococcus) = ‘clot buster’ after heart attack
Organic Acids & Enzymes
Learn one specific microbe per industrial acid.
Citric = fungus; acetic = bacterium. Do not flip them.
- Butyric acid → Clostridium butylicum (bacterium)
- Lipases in detergents; pectinases & proteases clarify juices
- Enzymes are microbial products used in industry
Microbes in Sewage Treatment
Heterotrophic microbes clean municipal waste-water in two stages.
High BOD = dirty water (more organic matter, more polluting).
- Aeration tank: aerobic microbes form flocs, reduce BOD
- Flocs settle as activated sludge; part recycled as inoculum
- Rest digested anaerobically → biogas
Biogas & Methanogens
Anaerobic bacteria turn dung and waste into burnable fuel gas.
Methanogens are strictly anaerobic — never in the aerated tank.
- Live in anaerobic sludge and in rumen of cattle
- Rumen methanogens digest cellulose → dung (‘gobar’) rich in them
- Developed in India by IARI and KVIC; spent slurry used as fertiliser
Microbes as Biocontrol Agents
Living organisms control pests and diseases instead of toxic chemicals.
Baculoviruses (Nucleopolyhedrovirus) = species-specific, narrow-spectrum (IPM).
- Ladybird → aphids; dragonfly → mosquitoes
- Trichoderma (fungus) controls plant pathogens
- Bt gene inserted into Bt-cotton for built-in resistance
Microbes as Biofertilisers
Organisms enrich soil nutrients, mainly fixing nitrogen and supplying phosphorus.
Mycorrhiza (Glomus) supplies PHOSPHORUS, not nitrogen.
- Cyanobacteria (Anabaena, Nostoc, Oscillatoria) fix N2 in paddy fields
- Azolla fern fixes N2 via the Anabaena inside it
- Glomus mycorrhiza also gives drought/salinity tolerance
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Frequently Asked Questions
It deals with the many beneficial uses of microorganisms for humans, including their role in household foods, industrial products such as alcohol, antibiotics, organic acids and enzymes, sewage treatment, biogas production, biocontrol of pests, and biofertilisers.
Curd is made by Lactobacillus, a lactic acid bacterium (LAB) that converts milk to curd and also raises its vitamin B12 content, while bread and dough rise because of the yeast Saccharomyces cerevisiae producing carbon dioxide. So curd is set by a bacterium and bread is leavened by a fungus (yeast).
Primary treatment is a physical process that removes floating debris and settles solids by filtration and sedimentation, producing primary sludge and effluent. Secondary or biological treatment passes the effluent into aeration tanks where aerobic microbes form flocs and consume the organic matter, sharply reducing the BOD of the water.
Biofertilisers are organisms that enrich the nutrient quality of the soil. Key examples are Rhizobium, which fixes nitrogen in the root nodules of legumes, free-living nitrogen fixers like Azotobacter and Azospirillum, cyanobacteria, and mycorrhizal fungi of the genus Glomus that help the plant absorb phosphorus.
Yes, it is part of the NEET Biology syllabus and a high-yield, scoring chapter because it is mostly factual. Most questions are direct match-the-microbe-to-its-product items, such as Aspergillus niger for citric acid, Penicillium notatum for penicillin, and Methanobacterium for biogas, so memorising these pairings pays off.