Class 8 Science – Chapter 2
Microorganisms: Friend and Foe
Page 3: Useful Microorganisms

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🧫 Microorganisms in Food

Some microorganisms are very useful in preparing food items. They help in fermentation, which changes the taste and texture of food.

• Lactobacillus bacteria convert milk into curd.
• Yeast is used in making bread, cakes, and alcohol.
• Fermented foods are easy to digest.

💊 Microorganisms in Medicines

Microorganisms are used to prepare medicines like antibiotics. Antibiotics kill or stop the growth of harmful microorganisms.

• Example: Penicillin is made from fungi.
• Antibiotics help us fight bacterial diseases.
• They do not work against viral diseases.

💉 Microorganisms in Vaccines

Vaccines are prepared from weakened or dead microorganisms. They help our body develop immunity against diseases.

• Vaccines protect us from diseases like polio, measles, and hepatitis.
• They help prevent the spread of infectious diseases.

🌱 Microorganisms in Agriculture

Certain bacteria help farmers by increasing soil fertility.

• Rhizobium fixes nitrogen in the soil.
• It helps plants grow healthy and strong.
• Reduces the need for chemical fertilizers.

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📌 Next Page: Harmful Microorganisms and Diseases