Last Updated: May 2026
NEET Biology Microbes in Human Welfare 2027 — Class XII NCERT Chapter 10 — accounts for an average of 2-3 questions every NEET cycle, making it one of the lowest-effort, highest-yield Biology topics. Microbes are tested in three dominant zones: industrial fermentation, sewage treatment, and biological control of pests. This guide covers complete NCERT notes, must-know microbe-product pairings, biocontrol agents, and 40 practice MCQs aligned with the latest NEET pattern.
Quick Facts: NEET Microbes 2027
| Aspect | Detail |
|---|---|
| NCERT chapter | Class XII Biology, Chapter 10 |
| Average NEET questions | 2-3 per year (last 5 NEET papers) |
| Difficulty | Easy-Moderate (high-yield) |
| Most-tested zones | Industrial products, biofertilisers, biogas, sewage treatment |
| NEET 2025 questions | 3 (Statin, Streptokinase, Methanogen) |
Microbes in Household Products
- Curd: Lactobacillus (LAB) ferments lactose → lactic acid; coagulates milk protein. Produces vitamin B12.
- Dough (idli, dosa, bread): Saccharomyces cerevisiae (baker’s yeast) ferments sugars to CO₂ → leavening.
- Toddy: Fermentation of sap from palm trees by yeasts.
- Cheese: Propionibacterium shermanii produces large holes (Swiss); Penicillium roqueforti ripens Roquefort.
Microbes in Industrial Products
Fermented Beverages
| Beverage | Microbe | Process |
|---|---|---|
| Wine, Beer | Saccharomyces cerevisiae | Without distillation |
| Whisky, Brandy, Rum | S. cerevisiae | With distillation |
Antibiotics
| Antibiotic | Source Microbe | Discoverer |
|---|---|---|
| Penicillin | Penicillium notatum | Alexander Fleming (1929); Chain & Florey purified |
| Streptomycin | Streptomyces griseus | Selman Waksman (1944) |
| Tetracycline | Streptomyces aureofaciens | — |
Chemicals, Enzymes & Bioactive Molecules (HIGH-YIELD)
| Product | Microbe | Use |
|---|---|---|
| Citric acid | Aspergillus niger | Food preservation |
| Acetic acid | Acetobacter aceti | Vinegar |
| Butyric acid | Clostridium butylicum | — |
| Lactic acid | Lactobacillus | Curd |
| Lipase, Pectinase, Protease | Various fungi/bacteria | Detergents, juice clarification |
| Streptokinase | Streptococcus | Clot buster (“clot dissolver”) |
| Cyclosporin A | Trichoderma polysporum | Immunosuppressant in organ transplant |
| Statins | Monascus purpureus | Cholesterol lowering — competitive inhibitor of HMG-CoA reductase |
Microbes in Sewage Treatment
Sewage treatment plants (STPs) use microbes in a 2-stage process:
- Primary treatment: Physical removal of solids by sedimentation.
- Secondary (biological) treatment:
- Aerobic microbes form flocs that consume organic matter, reducing BOD.
- Effluent passes to anaerobic sludge digester where methanogens produce biogas (CH₄ + CO₂ + H₂S).
Microbes in Biogas Production
- Methanogens: Methanobacterium, Methanococcus — produce CH₄ in anaerobic conditions.
- Substrate: Cattle dung (rich in cellulose-digesting bacteria) — hence “gobar gas”.
- Biogas plant developed in India by IARI & KVIC.
Biofertilisers (HIGHLY TESTED)
| Type | Example | Function |
|---|---|---|
| Symbiotic N₂-fixing bacteria | Rhizobium | Root nodules of legumes |
| Free-living N₂-fixers | Azotobacter, Anabaena | Soil and rice fields |
| Symbiotic fungi (mycorrhiza) | Glomus | Phosphorus absorption |
| Symbiotic cyanobacteria-fern | Anabaena–Azolla | Nitrogen fixation in paddy fields |
Biocontrol Agents
- Bt (Bacillus thuringiensis): Cry proteins kill caterpillars (lepidopteran pests).
- Trichoderma: Free-living fungi against plant pathogens.
- Baculovirus (Nucleopolyhedrovirus): Narrow-spectrum, species-specific insect control — eco-friendly.
- Ladybird beetle: Controls aphids (animal example, not microbe but commonly clubbed).
FAQ — NEET Microbes in Human Welfare 2027
Q1. Which microbe produces statins, and how do they work?
Monascus purpureus produces statins, which are competitive inhibitors of HMG-CoA reductase — the rate-limiting enzyme in cholesterol biosynthesis.
Q2. What is the role of methanogens in sewage treatment?
Methanogens are anaerobic archaea (e.g., Methanobacterium) that act on the activated sludge in the anaerobic digester to produce biogas — a mixture of CH₄ (50-70%), CO₂, and H₂S.
Q3. Which microbe is used to produce cyclosporin A?
Trichoderma polysporum. Cyclosporin A is an immunosuppressant used to prevent organ rejection during transplantation.
Q4. What is the symbiotic association between Anabaena and Azolla?
Anabaena (cyanobacterium) lives in cavities of Azolla pinnata (water fern) and fixes atmospheric nitrogen, enriching paddy fields. This is one of the most cited NEET examples of biofertilisers.
Q5. Which microbe is used in detergents for stain removal?
Lipases and proteases produced by various fungi/bacteria. Lipase removes oil stains; protease removes blood/protein stains.
Practice MCQs
[cg_quiz id=”neet-microbes-human-welfare-2027″]
Related Reading
- NEET Biology Evolution 2027
- NEET Genetics & Heredity 2027
- NEET Plant Physiology 2027
- NEET 2027 Syllabus
- Free NEET Mock Test
Bottom line: Memorise the microbe-product pairings table — it alone fetches 2 marks every NEET. Don’t skip biocontrol agents and biofertilisers; they reappear in NEET 2027.