Nitrospirae

Nitrospirae is a phylum of Gram negative bacteria best known for genera capable of nitrite oxidation, the step in the nitrogen cycle that converts nitrite into nitrate. Members of the phylum are found in soils, freshwater, marine sediments, and engineered environments such as wastewater treatment plants, where nitrite oxidizing Nitrospirae play an important role in nitrogen cycling. Some members of the phylum have also been shown capable of complete ammonia oxidation directly to nitrate, a process once thought to require two separate groups of organisms working together.