Microbes in Human Welfare Handwritten Best Notes :Class 12
1. Role of Microbes in Household Products
- Lactic Acid Bacteria (LAB):Lactobacillus → used in curd formation from milk.
- Improves nutritional quality (Vit. B12).
- Inhibits harmful microbes in the stomach.
- Fermented foods:
- Dough (idli, dosa, bread): Saccharomyces cerevisiae (yeast).
- Beverages (wine, beer, whisky, rum): Yeast fermentation → ethanol production.
2. Microbes in Industrial Products
- Fermented beverages:
- Saccharomyces cerevisiae → used in brewing & alcohol production.
- Antibiotics:
- First antibiotic: Penicillin (from Penicillium notatum by Alexander Fleming).
- Other examples: Streptomycin (Streptomyces griseus), Tetracycline, Erythromycin.
- Chemicals / Organic Acids:
- Citric acid → Aspergillus niger.
- Acetic acid → Acetobacter aceti.
- Lactic acid → Lactobacillus.
- Butyric acid → Clostridium butylicum.
- Enzymes:
- Lipase → detergent industry.
- Pectinase, Protease, Cellulase → used in juice clarification & bio-processing.
- Bioactive molecules:
- Cyclosporin A (from Trichoderma polysporum) → immunosuppressive.
- Statins (from Monascus purpureus) → lower blood cholesterol.
3. Microbes in Sewage Treatment
- Primary treatment: Physical → removal of large & small particles by filtration & sedimentation.
- Secondary treatment (Biological):
- Aerobic microbes (bacteria & fungi in aeration tanks) → digest organic matter → form flocs.
- Produces activated sludge.
- Anaerobic sludge digesters → anaerobic bacteria → methane, H₂S, CO₂ (biogas).
- Reduces BOD (Biological Oxygen Demand) of sewage.
4. Microbes in Production of Biogas
- Biogas: Methane-rich fuel produced by anaerobic microbes.
- Microbes involved: Methanogens (e.g., Methanobacterium).
- Raw material: Cattle dung (gobar gas plants) & other organic wastes.
- Used as renewable, eco-friendly energy source in rural areas.
5. Microbes in Biocontrol Agents
- Biocontrol: Use of natural organisms instead of chemicals (pesticides).
- Examples:
- Bacillus thuringiensis (Bt) → produces insecticidal proteins.
- Ladybird beetle & Dragonfly → control aphids & mosquitoes.
- Trichoderma (fungus) → biocontrol of soil-borne pathogens.
6. Microbes in Biofertilisers
- Symbiotic bacteria: Rhizobium (in legume root nodules).
- Free-living bacteria: Azospirillum, Azotobacter.
- Cyanobacteria (Blue-green algae): Anabaena, Nostoc, Oscillatoria → nitrogen fixation.
- Mycorrhiza: Symbiotic association of fungi with roots → absorb phosphorus & water.
Microbes in Human Welfare Handwritten Best Notes
Summary
- Microbes play a vital role in food production, industry, energy generation, sewage treatment, pest control, and agriculture.
- They are eco-friendly alternatives to chemical fertilizers, pesticides, and synthetic processes.