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World of Microorganisms

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World of Microorganisms - Lesson Summary

Microorganisms are the living organisms that are too small and invisible to the naked eye. Microorganisms are seen with the help of an instrument called as microscope. Microscopes can be of different types based on their complexity.

Microorganisms are omnipresent. Microorganisms are found everywhere, in the air, water, soil, in and on living organisms. Microorganisms can survive extreme conditions like hot springs to polar regions. They can survive too acidic and too alkaline environment. Under unfavourable conditions of temperature and water, they form hard and tough coverings called as cysts. As the favourable conditions prevail, they break open their cysts and continue their normal life cycles. 

Classification of microorganisms
1. Based on the characteristics, microorganisms can be classified into four groups – Bacteria, Fungi, Algae and Protozoa.
2. Based on the number of cells present, microorganisms can be unicellular or multicellular. Organisms which are made up of a single cell are unicellular while the organisms made up of many cells are multicellular forms. Most of the protozoans are unicellular in nature while most fungi and some algae are multicellular organisms.

3. Based on the significance, microorganisms can be useful or harmful to us.

Useful microorganisms
Microorganisms are extensively used in various fields and are of great economic importance.


Uses of microorganisms

a. Microorganisms are used in baking industry.
b. Microorganisms are used in the preparation of curd.
c. Microorganisms are used in commercial preparation of pickles, and many dairy products.
d. Microorganisms are used in industrial production of alcohol and wine. Yeast converts the natural sugars present in grains into alcohol. Wine is produced by the process of fermentation.The process of converting sugar into alcohol is called fermentation.
       •  Fermentation: Louis Pasteur discovered the process of fermentation. Fermentation is a slow biochemical process by which sugar molecules are broken down in the absence of air to produce alcohol and carbon dioxide. The process of fermentation is brought about by organisms like yeast which respire under anaerobic conditions.
e) Microorganisms like bacteria act as decomposers to clean up organic waste by decomposing them into usable substances.
       •  Decomposition: It is the process by which some organisms can convert dead and decaying matter into organic matter of the soil. These organisms which bring about decomposition are termed to be decomposers. Decomposers form an important part of the ecosystem.
f) Microorganisms are used to prepare medicines. These medicines are used in treatment of diseases caused by various microorganisms.
       •  Antibiotics: These are the substances produced by certain microorganisms and are used as medicines to kill pathogens. Antibiotics are used only against certain microorganisms. They are not effective against viruses.
g) Microorganisms are used in preparation of vaccines.
       •  Vaccines:  A vaccine is a collection of antigens of weak strains of particular disease causing microorganisms. When this is injected into the blood stream, it stimulates immune system to produce antibodies. These antibodies fight against weak antigens and some of them are stored in the blood to prevent the attack of that particular disease in future. This is the process by which vaccines develop immunity for a particular disease in our body.

Economic importance of bacteria
       •  Bacteria like lactobacilli are used in the preparation of curd.
       •  Bacteria are also used to prepare pickles and many dairy products.
       •  Bacteria are used in industrial production of alcohol and wine by the process of fermentation.
       •  Bacteria are useful in laboratories to test the effects of medicines.
       •  Bacteria act as decomposers to clean up the environment by performing the process of decomposition. Bacteria performing the process of decomposition are called as saprobes.
       •  Bacteria present in the soil aid in increasing soil fertility.
       •  Bacteria present in the soil fix the nitrogen to plants.
       •  Bacteria help in the tanning process of leather industries.
       •  Bacteria can also help in the digestion of sewage.

Economic importance of fungi
       •  Fungi are used in industries in the production of bakery products. Yeast is a microorganism which multiplies rapidly in dough and produces carbon dioxide. This dough, when baked, yields porous and spongy cakes. Yeasts are used in baking industry to provide puffiness to bread, cake and other bakery products.
       •  Fungi can be used as food in the form of Mushrooms and Morels.
       •  Fungi can be used in the production of antibiotics.
       •  Fungi are used in the production of wine by the process of fermentation.
       •  Fungi can be used in the commercial production of organic substances like citric acid, fumaric acid, lactic acid, oxalic acid etc.
       •  Fungi are used in agriculture to enhance the fertility of the soil.

Economic importance of algae
       •  Algae are photosynthetic microorganisms that can synthesise their own food which can be consumed by us. Algae are used as food as they are rich in carbohydrates, vitamins and few other inorganic substances. Spirogyra is the chief source of food. Some algae are found to be rich in protein content when compared to egg.
       •  Algae release lot of oxygen into water as a by-product of photosynthesis. This is the source of dissolved oxygen for aquatic organisms.
       •  Agar –Agar is used in preparation of ice-cream and jellies. e.g. Gelidium
       •  Algae are chewed instead of tobacco. e.g. Rhodomenia
       •  Algae are used extensively in industries to prepare some products like sugar, soap, cement, rubber blotting paper etc.
       •  Algae are used in agriculture to increase soil fertility e.g. Nostoc, Anabena.
       •  Algae are used to prepare algin used to prepare rollers for typewriters.
       •  Algae are used in the manufacture of paper and fabric paints.
       •  Some algae are used in the preparation of medicines.

Economic importance of protozoa
       •  Protozoans feed on fungi and bacteria which are harmful to human beings. Protozoans also help in decomposition of organic substances.
       •  Protozoans exist as symbionts providing habitat for other living organisms.
       •  Protozoans provide an important link in aquatic food chains.


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