Diversity, Functions, and Stress Responses of Soil Microorganisms

Abstract

Plant-associated soil microorganisms colonize the rhizosphere, face many stresses, and play the significant role in the functioning of plants by influencing their growth and metabolism. Microorganisms are beneficial to decompose organic matter, for mineralization, and for the availability of plant nutrients in the soil. They also maintain the soil ecosystem and biogeochemical cycle. The soil microflora and microfauna cause synergistic or antagonistic effects on plants and face various biotic and abiotic stresses in the rhizosphere. Soil microbes make a gene pool involved in microbes-plant interactions. The main categories of soil microorganisms are bacteria, algae, protozoa, fungi, viruses, and multicellular animal parasites. The activities of soil microorganisms are influenced by interactions between soil physicochemical properties and environmental conditions. Bacteria are present in all types of soil and play their roles in atmospheric nitrogen fixation. In this review, the stress conditions in the rhizosphere, diversity of microorganisms, and their role in increasing soil fertility have been emphasized. Most of the microflora and microfauna are pathogenic in nature, but their positive interactions into the soil (in the rhizosphere) are very significant. Therefore, review of recent studies on diversity, stresses, and functions of soil microorganisms are described in this article.