Pocket Notes — Microbes in Human Welfare
Household products
| Product | Microbe |
|---|---|
| Curd | Lactobacillus (LAB) |
| Bread / dough | Saccharomyces cerevisiae |
| Idli, dosa | LAB + yeast |
| Swiss cheese | Propionibacterium shermanii (large holes from CO₂) |
| Roquefort cheese | Penicillium roqueforti |
| Toddy | Yeast on palm sap |
Fermented beverages
| Type | Distilled? | Made by |
|---|---|---|
| Wine, beer | ❌ | Saccharomyces cerevisiae |
| Whisky, brandy, rum | ✔️ | Same |
Antibiotics
- Penicillin: from Penicillium notatum
- Discovered by Alexander Fleming (1928); developed by Chain & Florey
- All three shared Nobel Prize (1945)
Industrial products (mnemonic)
| Product | Microbe |
|---|---|
| Citric acid | Aspergillus niger |
| Acetic acid | Acetobacter aceti |
| Butyric acid | Clostridium butylicum |
| Lactic acid | Lactobacillus |
| Ethanol | Saccharomyces cerevisiae |
Bioactive molecules
| Molecule | Microbe | Use |
|---|---|---|
| Lipase | Bacterium/fungus | Detergent (oil stain remover) |
| Pectinase, Protease | Fungi | Fruit juice clarification |
| Streptokinase | Streptococcus | Clot buster — heart attack |
| Cyclosporin-A | Trichoderma polysporum | Immunosuppressant — organ transplants |
| Statins | Monascus purpureus | Cholesterol lowering |
Sewage treatment stages
- Primary — physical (filtration, sedimentation) → primary sludge + effluent.
- Secondary (biological) — aeration tank → flocs of aerobic microbes reduce BOD → settling tank → activated sludge.
- Anaerobic digestion of remaining sludge → biogas.
- Tertiary — chemical polishing (N, P removal).
Biogas
- Composition: CH₄ + CO₂ + H₂ + H₂S
- Microbes: Methanogens — Methanobacterium
- Substrate: cattle dung (gobar)
- Plants designed by KVIC and IARI
Biocontrol agents
| Agent | Controls |
|---|---|
| Ladybird | Aphids |
| Dragonfly | Mosquitoes |
| Bacillus thuringiensis (Bt) | Butterfly caterpillars; used in Bt cotton |
| Trichoderma | Plant pathogens |
| Baculoviruses (NPV) | Species-specific insecticide |
Biofertilisers
- Symbiotic N₂ fixer: Rhizobium (in root nodules of legumes)
- Free-living N₂ fixers: ***Azotobacter*, Azospirillum**
- Cyanobacteria: Anabaena, Nostoc, Oscillatoria — paddy field N₂ fix
- Aquatic fern: Azolla (with symbiotic Anabaena)
- Mycorrhiza: Glomus (absorbs P, drought tolerance)
FAQ traps
- Which fungus gives penicillin? — Penicillium notatum (later P. chrysogenum).
- Cholesterol drug from microbe? — **Statins from Monascus purpureus**.
- Cyclosporin-A source? — Trichoderma polysporum.
- Swiss cheese holes are from? — **CO₂ by Propionibacterium shermanii**.
- LAB improves which vitamin? — B₁₂.