Nitrosomonas

Nitrosomonas is a genus of Gram-negative bacteria belonging to the class Betaproteobacteria. It is one of the five genera of ammonia-oxidizing bacteria and, as an obligate chemolithoautotroph, uses ammonia (NH3) as an energy source and carbon dioxide (CO2) as a carbon source in the presence of oxygen. Nitrosomonas species are important in the global biogeochemical nitrogen cycle because they increase the bioavailability of nitrogen to plants and play a role in denitrification, a process important for the release of nitrous oxide, a powerful greenhouse gas. These microbes are photophobic and usually generate a biofilm matrix, or form clumps with other microbes, to avoid light. Nitrosomonas can be divided into six lineages: The first includes Nitrosomonas europaea, Nitrosomonas eutropha, Nitrosomonas halophila, and Nitrosomonas mobilis. The second presents Nitrosomonas communis, N. sp. I, and N. sp. II. The third includes only Nitrosomonas nitrosa. The fourth includes Nitrosomonas ureae and Nitrosomonas oligotropha. The fifth and sixth lineages include Nitrosomonas marina, N. sp. III, Nitrosomonas aestuarii, and Nitrosomonas cryotolerans.