Azotobacter

Azotobacter is a genus of free-living diazotrophic bacteria whose resting stage is a cyst. It is primarily found in neutral to alkaline soils, in aquatic environments, and on some plants. It has several metabolic capabilties, including atmospheric nitrogen fixation by conversion to ammonia. Their unique system of three distinct nitrogenase enzymes makes these bacteria of particular interest to scientists, who may work toward a better understanding of nitrogen fixation and its role in agriculture. Azotobacter spp. have the highest metabolic rate of any organisms.

See: Microbewiki