**1. Introduction**

Life on earth is not only dependent on the celestial environment around the earth but it is also completely influenced by the soil under our feet. Earth is a pool of different complex ecosystems and the proper functioning of those ecosystems are very much required for sustenance and evolution of the life. Soil is an important ecosystem of the earth and essential for life and one of the most valuable resources available to us, which acts as a water filter, supports plant and animal life, source of the minerals and medicines. Soil is a living entity and existence of which is defined by the occurrence of the organisms in it. The formation of soil is not only dependent on the physical or chemical activity on the rocks, but also by the continuous activity of diverse microbial species which add or enhance the

properties of soils in terms of formation of structure and function. Soil provides shelter to various soil harboring insects, reptiles, animals and a huge volume of microbes within the soil aggregates. It is the home for innumerable microbial species largely unnoticed and busy in maintaining the ecological balance of the earth. It is a complex and dynamic system, which directly or indirectly influences the food chain, nutrient cycles, and ecological equilibrium. Understanding the unexplored microbial world is high priority and is needed to come up with the ways of coping up with various climatic changes and for the welfare of every organism on the earth.
