Microorganisms are used for various purposes such as:

* They are used in the preparation of curd, bread and cake.

* They are used in the preparation of alcohol, wine and acetic acid (vinegar).

* They are also used in cleaning up of the environment.

* In agriculture, they are used to increase soil fertility by fixing nitrogen.

* The antibiotics are manufactured by growing specific microorganisms and are used to cure a variety of diseases. Penicillin is an antibiotic made from Penicillium.

* Certain microbes are also used in the biological treatment of sewage and industrial effluents.

* Yeast is used in making idlis, bhaturas, bread, pastries and cakes.