High Quality Content by WIKIPEDIA articles! Azotobacter is a genus of usually motile, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime. They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil. Apart from being a model organism, it is used by humans for the production of biofertilizers, food additives and some biopolymers. The first representative of the genus, Azotobacter chroococcum, was discovered and described in 1901 by the Dutch microbiologist and botanist Martinus Beijerinck. Azotobacter are Gram-negative bacteria. They are found in neutral and alkaline soils, in water and in association with some plants.