Archaea nitrification

Most of the aerobic nitrification that occurs in natural habitats is thought to be performed by obHgately autotrophic, or in a few cases, mixotrophic, bacteria and archaea. The classical autotrophs are best known and have been assumed to be responsible for the major fluxes in this pathway, so we shall consider them first. 

As an alternative to partial assimilatory NOs reduction by phytoplankton, oxidation of NH4+ by Bacteria and Archaea (the first step in the 2-step process of nitrification) can produce N02 as an intermediate product. Nitrifying bacteria were first isolated from the marine environment by Watson (1965) and are now known to be ubiquitous in the global ocean. Wada and Hattori (1971) used a sensitive chemical assay to measure changes in N02 in incubated samples, to conclude that NH4+ was the major source of N02 in the PNM in the central North Pacific Ocean. Miyazaki et al. (1973, 1975), using a N tracer method, found that, in Sagami Bay and in the western North Pacific, NH4+ and NOs were both important sources ofN02. ... 

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