General Information: Nitrite-oxidizing bacterium. Members of this genus are found in marine, freshwater, and terrestrial habitats, often in association with ammonia-oxidizing bacteria. These organisms oxidize nitrate, generated by the oxidation of ammonia, to nitrate and play an important role in the global nitrogen cycle. The enzyme involved in nitrite oxidation, nitrite oxidoreductase, can also reduce nitrate to nitrite in the absence of oxygen, allowing Nitrobacter sp. to grow anaerobically. Nitrobacter winogradskyi is commonly isolated from soil, fresh and sea water, sewage, and compost. This organism can grow anaerobically using nitrate as the electron acceptor, forming nitrite, nitric oxide, and nitrous oxide.