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.

Microbes in Human Welfare Handwritten Best Notes pdf