Azotobacter

Azotobacter

Azotobacter species cells, stained with Heidenhain's iron hematoxylin, ×1000
Scientific classification
Domain:	Bacteria
Phylum:	Proteobacteria
Class:	Gammaproteobacteria
Order:	Pseudomonadales
Family:	Pseudomonadaceae/Azotobacteraceae
Genus:	Azotobacter Beijerinck, 1901
Species
Azotobacter agilis Azotobacter armeniacus Azotobacter sp. AR Azotobacter beijerinckii Azotobacter chroococcum Azotobacter sp. DCU26 Azotobacter sp. FA8 Azotobacter nigricans Azotobacter paspali Azotobacter salinestris Azotobacter tropicalis Azotobacter vinelandii

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 (nitrogen fixation). In addition to being a model organism for studying diazotrophs, 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 species are Gram-negative bacteria found in neutral and alkaline soils, in water, and in association with some plants.