Nitrogen fixation is a process by which molecular nitrogen in the air is converted into ammonia (NH3) or related nitrogenous compounds in soil. Atmospheric nitrogen is a relatively nonreactive molecule that is metabolically useless to all but a few microorganisms. Biological nitrogen fixation converts N2 into ammonia, which is metabolized by …

The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, …

Positive and negative interactions take place not only between microbes but also between microbes and plants. The rhizosphere is a zone of predominantly commensal and mutualistic interactions þetween microbes and plants. Plant roots provide such suitable habitats for the growth of microorganisms that high numbers of different microbial populations are …