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Microorganisms : Friend and Foe

Micro-organisms and their habitat

You might have watched advertisements on television saying tap water is unsafe, or use aqua-guard, a water purifying system in order to get water safe for drinking. Then they show various germs that are magnified and labelled as culprits for our bad health. Have you ever thought what these tiny monsters or germs are?

Living organisms which are not visible to the naked eye are known as micro-organisms.

These germs are microorganisms or microbes. They are the tiniest possible living organisms that are too small to be seen through naked eyes. They are living organisms that can be seen only with a microscope or a magnifying glass.

Microorganisms were observed for the first time by Anton von Leeuwenhoek in 1674, using a microscope of his own.

Is the water that seems to be clean, clear, and transparent safe for drinking?

No! The water that seems to be clear and transparent is not always safe for drinking. It may contain some of the disease-causing microorganisms and other dissolved impurities that you cannot see with your naked eyes. However, if you view the water with the magnifying glass, you can see several microorganisms in it.

Therefore, it is advised to purify the water before drinking. The purification can be done by water purifying system or by boiling the water.

Microorganisms make up the largest number of living organisms on the planet. They are not just billions or trillions around the earth, but trillions of trillions and many more. There is a huge variety of microorganisms present on earth.

 There are five major groups of microorganisms that include bacteria, protozoa, fungi, algae and viruses.


Can you tell what is the study of these microorganisms called?


The study of microorganisms is called microbiology.

Do you Know that these microorganisms can be cultivated in artificial media under certain conditions?

Microorganisms can be grown in laboratories in a special medium called culture media. This medium provides an appropriate environment for the gowth of microorganisms in the laboratories. Depending upon the special requirements of particular microorganisms, different kinds of culture media are formulated. Some are given below:

Microorganisms Culture meida
Bacteria Nutrient Agar(NA)
Fungi Potato Dextrose Agar (PDA)
Protozoans Nutrient Broth media
Algae Beneck's Media
Virus Animal cells


There are many scientists who have contributed in the field of microbiology. Let us discuss about the contribution of some scientists here.


Louis Pasteur (1822-1895)

The main contributions of Louis Pasteur are:

  • He disapproved the theory of spontaneous generation of life. He proved this by his famous experiment known as swan neck flask experiment. Earlier it was thought that new life originates from non living things, but Pasteur disapproved this and established the theory of biogenesis.


  • He developed the method of pasteurization to prevent spoilage of food by bacteria.


  • He also contributed to the development of vaccines.

Robert Koch ((1843-1910)

The main contributions of Robert Koch in the field of microbiology include:


  • Robert Koch developed the germ theory of disease that established the microbial cause of disease.
  • He identified anthrax disease that infected cattle, sheep and even human…

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