The Bio Brief

Microorganisms play an important role in our daily lives.
Some microorganisms are helpful (friendly), while others are harmful and cause diseases.

Microorganisms

      |

      |—— Friendly (Useful)

      |—— Harmful (Disease causing)

Friendly Microorganisms

Friendly microorganisms help us in many ways such as:

• Making food
• Producing medicines
• Improving soil fertility
• Cleaning the environment

1. Making of Curd and Bread

Making of Curd

• Curd is made from milk
• A small amount of curd is added to warm milk
• Curd contains bacteria called Lactobacillus

Milk + Lactobacillus bacteria

            ↓

         Curd

• Lactobacillus multiplies in milk and converts it into curd
• Bacteria are also used in making:
  • Cheese
  • Pickles
  • Idli and dosa batter
  • Bhaturas and cakes

Making of Bread and Cakes

• Yeast is used in baking
• Yeast produces carbon dioxide gas
• The gas forms bubbles and makes the dough rise

Dough + Yeast

      ↓

Carbon dioxide released

      ↓

Dough becomes soft and fluffy

This process is called fermentation.

2. Commercial Use of Microorganisms

Microorganisms are used to produce:

• Alcohol
• Wine
• Vinegar (acetic acid)

Fermentation

• Yeast grows on sugars present in grains and fruits
• Sugar is converted into alcohol

Sugar + Yeast

      ↓

   Alcohol + CO₂

• Fermentation was discovered by Louis Pasteur (1857)

3. Medicinal Use of Microorganisms

Microorganisms are used to make medicines called antibiotics.

Antibiotics

• Kill or stop the growth of disease-causing microbes
• Made from bacteria and fungi

Examples:

• Penicillin
• Streptomycin
• Tetracycline
• Erythromycin

Discovery of Penicillin

• Discovered by Alexander Fleming (1929)
• A mould stopped the growth of harmful bacteria

Important Points About Antibiotics

• Take antibiotics only on a doctor’s advice
• Complete the full course
• Misuse can make antibiotics ineffective
• Antibiotics do not work against viruses
  • Cold and flu are caused by viruses

4. Vaccines

What is a Vaccine?

• A vaccine contains dead or weakened microbes
• It helps the body make antibodies
• Antibodies protect us from diseases

Vaccine given

      ↓

Antibodies formed

      ↓

Protection from disease

Diseases Prevented by Vaccines

• Polio
• Tuberculosis
• Cholera
• Hepatitis
• Smallpox
• Smallpox vaccine discovered by Edward Jenner (1798)
• Polio drops are part of the Pulse Polio Programme

5. Increasing Soil Fertility

• Some bacteria fix nitrogen from the air
• They increase soil fertility
• Called biological nitrogen fixers

Nitrogen in air

      ↓

Nitrogen-fixing bacteria

      ↓

Fertile soil

6. Cleaning the Environment

Microorganisms help in decomposition.

• They break down:
  • Vegetable peels
  • Plant waste
  • Dead animals
  • Animal waste

Organic waste

      ↓

Action of microbes

      ↓

Manure

      ↓

Used by plants

• Microbes cannot decompose plastic, glass, or metal
• Decomposition helps:
  • Clean the environment
  • Recycle nutrients

Microorganisms are very useful to humans. They help in:

• Making food
• Producing medicines
• Protecting us from diseases
• Improving soil fertility
• Cleaning the environment

Without microorganisms, life on Earth would not be possible.