Microbes in Human Welfare: Class 12 NCERT Biology Guide

Introduction to Microbes in Human Welfare

Microbes are microscopic organisms including bacteria, fungi, viruses, and protozoa. Despite their tiny size, they have immense importance in human welfare. In Class 12 NCERT Biology, the chapter _Microbes in Human Welfare_ highlights how microbes contribute to food production, medicine, industry, and environmental sustainability. These beneficial microbes help produce fermented foods, antibiotics, enzymes, and bioactive molecules that improve health and economy.

Microbes in Food Production and Fermentation

Microbes are essential in producing various traditional and commercial foods through fermentation:

• Lactic Acid Bacteria: Found in curd, yogurt, and fermented vegetables like pickles. They ferment lactose to lactic acid, preserving and enhancing food flavor.
• Yeast (Saccharomyces cerevisiae): Used in bread making and alcoholic beverages such as beer and wine. Yeast ferments sugars to produce ethanol and carbon dioxide, which makes dough rise.
• Traditional Indian Fermented Foods:
• Wheat-based: Idli, dosa, and bread.
• Rice-based: Idli and dosa batter fermentation.
• Bengal gram-based: Dhokla and kadhi.

Fermentation not only improves taste and texture but also increases food shelf life and nutritional value.

Industrial Applications of Microbes

Microbes are grown on an industrial scale in fermentors to produce valuable products:

• Alcoholic Beverages: Yeast ferments malted cereals or fruit juices to produce ethanol. Wine and beer are produced by fermentation, while whisky, brandy, and rum require distillation.
• Organic Acids:

| Acid | Microbe | Use | |----------------|-----------------------|----------------------------------| | Citric acid | Aspergillus niger | Food preservative and flavoring | | Acetic acid | Acetobacter aceti | Vinegar production | | Butyric acid | Clostridium butylicum | Used in pharmaceuticals | | Lactic acid | Lactobacillus | Food preservation and dairy |

• Enzymes: Lipases (detergents), pectinases and proteases (juice clarification), streptokinase (clot buster).
• Bioactive Molecules: Cyclosporin A (immunosuppressant) and statins (cholesterol-lowering agents).

The controlled environment of fermentors ensures optimal growth and product yield.

Microbes in Medicine: Antibiotics and Beyond

Microbes have revolutionized medicine by producing antibiotics and other therapeutic agents:

• Penicillin: Discovered by Alexander Fleming from the mold Penicillium notatum. It inhibits bacterial growth and was widely used during World War II.
• Other Antibiotics: Various microbes produce antibiotics that target different pathogens, saving millions of lives.
• Immunosuppressants: Cyclosporin A from Trichoderma polysporum helps in organ transplantation by preventing rejection.
• Enzymes in Therapy: Streptokinase, produced by microbes, dissolves blood clots in heart attack patients.

These microbial products are crucial in treating infectious diseases and improving healthcare outcomes.

Environmental Role of Microbes in Human Welfare

Microbes also contribute to environmental management, which indirectly benefits human welfare:

• Sewage Treatment: Microbes decompose organic waste in sewage, reducing pollution and recycling nutrients.
• Biogas Production: Methanogenic bacteria convert organic waste into methane gas, a renewable energy source.
• Bioremediation: Certain microbes degrade harmful pollutants in soil and water, cleaning the environment.

These processes help maintain ecological balance and promote sustainable living.

Comparison of Microbial Products and Their Uses

Here is a comparison table summarizing key microbial products and their applications:

This table helps understand the diverse roles microbes play in human welfare.