Soil Microorganisms: Characteristics, Importance and their Functional Role

Soil is the upper layer of the Earth's crust that has been altered by weathering, physical/chemical, and biological processes. It is made up of mineral particles, organic matter, water, air, and living organisms that are organised in genetic soil horizons. Different soils represent the effects of the various underlying factors in their formation, and as their physicochemical characteristics shift along different axes (surface and subsurface horizons), variability exists from site to site and within a given site in the range of micro niches. Such strange characteristics convert/transform soils into a composite of very diverse ecosystems, making its study difficult because very diverse communities can coexist in a very small scale of the same sample. Soil organisms involve macro/megafauna, mesofauna, and microfauna/flora, and despite accounting for less than 1% of the total mass of a soil, they play critical functional roles in maintaining the soil ecosystem. This study describes various approaches to structural and functional characterising key soil microorganisms such as bacteria, archaea, plant growth promoting bacteria, arbuscular mycorrhizas, and nematodes.