ABSTRACT
This chapter describes that nitrogenase is the key component play very significant function in the nitrogen fixation. Biological nitrogen fixation (BNF) is accountable for the major reduction of dinitrogen to the ammonia which is utilized by plants followed by animals indirectly. BNF has been recommended to be an ancient and possibly even primordial process. The production of oxygen may have opened up new ecological niches, allowing the global biome to diversify and radiate into new environmental realms. Vanadium nitrogenase is also a nitrogen-fixing enzyme that is used as an alternative to molybdenum nitrogenase which is expressed only under molybdenum deficient conditions. Vanadium nitrogenases are active under anaerobic conditions and are found in the bacterial genus like Azotobacter, also found in other species like Rhodopseudomonas palustris and Anabaena variabilis.Rhizobium spp. is a genus of Gram-negatives soil bacteria which involved in establishing and maintaining a symbiotic relationship with legume species.
