Azotobacter vinelandii is Gram-negative diazotroph that can fix nitrogen while grown aerobically. These bacteria are easily cultured and grown. A. vinelandii is a free-living N2 fixer known to produce many phytohormones and vitamins in soils. It produces fluorescent pyoverdine pigments. Nitrogenase The nitrogenase holoenzyme of A. vinelandii has been characterised by X-ray crystallography in both ADP tetrafluoroaluminate-bound and MgATP-bound states. The enzyme possesses molybdenum iron-sulfido cluster cofactors (FeMoco) as active sites, each bearing two pseudocubic iron-sulfido structures. Applications It is a genetically tractable system that is used to study nitrogen fixation. Genetically engineered strains can produce significantly higher amounts of ammonia. Appropriate ammonia emissions can provide crops with the ammonia they need without excess amounts that can pollute lakes and oceans. Variable ploidy A. vinelandii can contain up to 80 chromosome copies per cell. However this is only seen in fast growing culture, whereas cultures grown in synthetic minimal media are not polyploid. References External links Azotobacter vinelandii Genome Project Current research on Azotobacter vinelandii at the Norwich Research Park Type strain of Azotobacter vinelandii at BacDive - the Bacterial Diversity Metadatabase Pseudomonadales Bacteria described in 1903