What is Microbes in Human Welfare Class 12: Definition & Importance

Definition and Types of Microbes in Human Welfare

Microbes, also known as microorganisms, are tiny living organisms visible only under a microscope. In Class 12 NCERT Biology, microbes are classified based on their structure and function. The main types include:

• Bacteria: Single-celled organisms with diverse roles.
• Fungi: Includes yeasts and molds, important in food and medicine.
• Viruses: Acellular entities that can cause diseases but also used in vaccines.
• Protozoa: Single-celled eukaryotes, some beneficial, some harmful.

These microbes contribute significantly to human welfare through various processes like fermentation, antibiotic production, and environmental management.

Role of Microbes in Food Production and Preservation

Microbes are essential in producing and preserving many food items:

• Fermentation: Microbes like Lactobacillus and Saccharomyces ferment sugars to produce yogurt, cheese, bread, and alcoholic beverages.
• Food preservation: Some microbes produce acids or alcohol that inhibit spoilage.

For example, in yogurt production, Lactobacillus bacteria ferment lactose into lactic acid, which thickens milk and adds a tangy flavor.

Worked Example:

If 1 litre of milk contains 50 g lactose, and Lactobacillus converts 80% of it into lactic acid, the amount of lactic acid produced is:

$$ 50 \times 0.8 = 40 \text{ g} $$

This acid helps in coagulating milk proteins, forming yogurt.

Microbes in Medicine: Antibiotics and Vaccines

Microbes have revolutionised medicine:

• Antibiotics: Many antibiotics are derived from microbes, e.g., Penicillium fungi produce penicillin.
• Vaccines: Some vaccines use weakened or dead microbes to build immunity.

Microbes also help produce insulin and other drugs using genetic engineering techniques.

Agricultural Benefits of Microbes

Microbes improve soil fertility and crop yield:

• Nitrogen fixation: Bacteria like Rhizobium convert atmospheric nitrogen into forms plants can absorb.
• Biofertilisers: Microbial inoculants that enrich soil nutrients.
• Biopesticides: Microbes such as Bacillus thuringiensis produce toxins to control pests safely.

These natural methods reduce chemical fertiliser use and promote sustainable farming.

Environmental Applications: Bioremediation and Waste Management

Microbes help clean the environment:

• Bioremediation: Certain bacteria degrade pollutants like oil spills and pesticides.
• Sewage treatment: Microbes break down organic waste in sewage.
• Composting: Microbial activity converts organic waste into nutrient-rich compost.

This eco-friendly approach supports waste recycling and pollution control.

Harmful Effects and Control of Microbes

While microbes benefit humans, some cause diseases:

• Pathogens like Mycobacterium tuberculosis cause tuberculosis.
• Viruses cause flu, dengue, and other infections.

Control methods include:

• Vaccination
• Antibiotics and antiviral drugs
• Hygiene and sanitation practices

Understanding microbes helps prevent and manage diseases effectively.