Microorganisms have been invented by many scientists nowadays because there are many uses of it.Microorganisms are found in very large number in this entire biosphere.In the present scenario their presence cannot be simply ignored.

Microbes provide us a variety of food products and may be sometimes they act as the sources of food.At the other hand thy use our food supply as a source of nutrients for their growth.

They are also used in industries.Enzymes,amino acids,vitamins,antibiotics etc.... are all microbes. 

Microbes are also widely used in biotechnology.

The microbes play an important role in the recycling of components such as oxygen,carbon,nitrogen,sulphur,phosphorous etc....So they are also useful in agriculture.

Microbes are also widely used in the manufacture of medicines.The horrible epidemics such as the small pox,diphtheria,whooping cough etc.... are all reduced or cleared to a great extent by vaccination which is developed from microbes.

That is what the uses of invention of microbes.