Microorganisms: Friend or Foe

We all are aware of the fact that there are small organisms which are present in our environment known as microorganisms. In this article you would get a brief detail of microorganisms along with their uses and harmful effects. In this article I would also explain about various types of bacteria, fungi, algae, protozoa and viruses. So, read a brief detailed description about microorganisms and increase your general knowledge. Moreover, it's upon you to decide whether microorganisms are friend or foe.


The name Microorganisms itself indicates micro size organisms that is very small in size. Most of the Microorganisms are invisible to our naked eyes because of their very small size and some of them are invisible to our naked eyes because of their big size. Microorganisms can live in extreme climatic conditions and are found almost everywhere and anywhere.
They can be useful as well as harmful to us and categorized into these types:
1. Bacteria
2. Fungi
3. Algae
4. Protozoa
5. Viruses
Let us study in brief about them.


They are small organisms and hence invisible to our naked eye and can be only seen under a microscope. These are of 0.7 um to 1.5 um in width and 1 um to 10 um in length that is very small. These are unicellular plants having a rigid and tough cell wall and because of it they have their shapes.
Bacteria are of four types and grouped according to their shapes.
  • Coccus = Spherical or round in shape.

  • Bacillus = Cylindrical or rod in shape.

  • Spirillum = Spiral or coiled in shape.

  • Vibrio = Comma shaped or c-shaped.

  • Useful and harmful bacteria

    Bacteria help us in many ways. They help plants roots by making of manure, minerals in soil and fixation of nitrogen in soil. They are also needed in Industries to make lactic acid, alcohol, tanning of leather, rotting of flax, ripening of tea leaves, Lactobacillus bacteria is used to make curd by converting milk into curd, Acetobacter aceti bacteria helps in making vinegar, etc.

    Harmful bacteria cause many diseases such as typhoid, cholera, and diarrhea. Food poisoning occurs by eating spoiled food. So we should not eat spoiled food as it may have Clostridium botulinum which causes food poisoning. Some harmful bacteria are Clostridium botulinum which causes food poisoning, Salmonellatyphi which causes typhoid, Vibrio cholerae which causes cholera, Bacillus coli which causes diarrhea, etc.


    Fungi are of four types.
  • Rusts

  • Moulds

  • Mushrooms

  • Puffballs

  • Moulds, mushrooms and puffballs can be seen by naked eyes but we can't see rusts by naked eyes. Rusts are unicellular structures like bacteria. Moulds are like paper pins in shape. Puffballs are small ball-like structures which grow on rich organic matter and mushrooms are like small umbrellas.

    Useful and harmful fungi

    Fungi as yeast are used to make alcohol, idli, dhokla and many other South Indian dishes. Yeast is also used in bakery industries to make dough. The process of making dishes by yeast is known as fermentation process. Fungi such as Penicillium notatum is used to make as antibiotics called Penicillin. Some fungi as mushrooms are also used as food like in curry, soup and pulao.

    Fungi cause a large number of diseases in plants as well as in animals. They cause rust diseases in plants and ringworm disease of human beings. They also cause fruit rot of apple, early blight of potato, and red rot of sugar cane. They can as well as cause infection on skin, scalp, and nails in human beings. Some of harmful fungi spoils food like Aspergillus spoils jellies, pickles, bread, etc.


    Most of the algae are green in color due to presence of chlorophyll in them. They can be many celled or single celled. We can find some of single-celled algae in paddy fields and also helps to fix nitrogen. Algae are the aquatic plants found in freshwater, marine water and as well as in moist places in plants.

    Useful and harmful algae

    As they are found in water they are used to fix nitrogen in water. Some useful algae as Chlorella are used as food as they provide carbohydrates, vitamins (A, C, D, E), and protein. Some algae enrich water with oxygen as a result of photosynthesis. Some of them are useful to us due to their rich source of certain substances which are found in them. They are also used in Industries as they are used in glass, toothpaste, metal paints, polish, cosmetics manufacture etc.

    Some harmful algae are oscillatoria, Anabaena, Microsystis, etc. Harmful effects of algae can be seen as algal bloom in water. Rapid growth of algae sometimes causes poisonous effect after dying by releasing toxins, therefore, water cannot be consumed by human beings and other animals but as a result infected water is consumed by aquatic plants & animals and results in death of aquatic organisms.


    Proto means first, Zoan means animals. They are also very small and can only be seen by a microscope. These are the most primitive types of animals; some of them are Amoeba, Entamoeba coli, Paramoecium, Euglena, etc. They are single celled organisms and found everywhere like in water, land as well as in the body of human and other animals.

    Useful and harmful protozoa

    Some of them are symbiotic in nature, thus, help in benefitting other organisms in many ways. Some forms of protozoa help in the final degradation of waste and sewage. They are also used as research material for various biological activities.

    Harmful protozoa like E. gingivalis causes pyorrhea, infection of gums and bad breath. E. histolytica lives in the large intestine of human and causes Amoebic dysentery. Plasmodium causes malaria fever and Trypanosoma causes sleeping sickness.


    Virus was first discovered in 1892 by a Russian biologist D.J. Ivanovsky in mosaic disease of tobacco leaves and hence, named as TMV (Tobacco Mosaic Virus). They are not organisms. They are chemical particles which can be living only in live cells and tissues of the plants or animals.

    Useful and harmful viruses

    Usefulness of virus can be realized by their very simple nature, easy availability, crystallization, storing and multiplication in cells and because of these reasons they are used for scientific researches such as in biotechnology, gene therapy, genetic engineering and for making insect killing viruses, antibiotics, etc.

    Harmful viruses cause viral diseases of animals like common cold, herpes, smallpox, hepatitis, influenza, polio and rabies. Some viruses are also implicated in the development of cancer. They also cause plant's viral diseases like yellowing and blistering of leaves and stem. Only antiviral drugs are effective against certain viral diseases and vaccines.

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