Diazotrophs are nitrogen-fixing micro organisms responsible for promoting plant growth and other living organisms. These groups of organisms are found in soil but most environments have not been explored to ascertain their presence and activity. This study, therefore, intends to assess the availability of diazotrophs in the arable soil within Uzairue community in Edo State with the objective of evaluating the density, populations, and identity of diazotrophic bacteria in soil samples from different cultivable locations using different microbiological approaches. Soil samples from the various arable soil were collected using a composite sampling method specifically from farmlands and physicochemical parameters were determined such as nitrate, phosphate, organic matter, organic, and other properties that can influence microbial activities and density. The soil samples were enumerated the total heterotrophic bacterial population and isolation of nitogen fixation (NF) bacteria was done using N-free media. The samples had trace levels of phosphate, nitrogen, and other varying concentrations of physicochemical parameters. An appreciable population was observed in the samples which ranged from 4.6 x 106 to 5.1 x 106 . Out of a total of thirty (30) bacterial isolates, nine (9) showed potential for nitrogen fixation on the Nfree medium and were identified using their morphological features, biochemical reaction, and molecular characterization. The result of the research showed that the identified species have high phenotypic diversity and were identified to belong to four genera: Alcaligenes, Pseudomonas, Priestia, and Providencia. Conclusively the research showed that diazotrophic bacteria with nitrogenase activity are present in arable soil which could be harnessed and exploited for green and sustainable agriculture

Keywords : Diazotrophs, nitrogenase, microorganisms, molecular, agriculture.