Nitrification 361028 221012037 2008-06-22T17:28:58Z 212.20.74.230 [[cs:Nitrifikace]] {{Refimprove|date=July 2007}} [[Image:Nitrogen Cycle.jpg|right|thumb|350px|right|[[Nitrogen cycle]]]] '''Nitrification''' is the biological [[redox|oxidation]] of [[ammonia]] with oxygen into [[nitrite]] followed by the oxidation of these nitrites into [[nitrate]]s. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the [[nitrogen cycle]] in [[soil]]. This process was discovered by the [[Russia]]n [[microbiologist]], [[Sergei Winogradsky]]. The oxidation of ammonia into nitrite is performed by two groups of organisms, ammonia oxidizing [[bacteria]] and ammonia oxidizing [[archaea]]<ref>Treusch et al. 2005</ref>. Ammonia oxidizing bacteria can be found among the β- and γ-proteobacteria <ref>Purkhold et al., 2000</ref>. In soils the most studied ammonia oxidizing bacteria belong to the genera ''[[Nitrosomonas]]'' and ''[[Nitrosococcus]]''. Although in soils ammonia oxidation occurs by both bacteria and archaea in harsher environments like oceans ammonia oxidation is dominated by archaea<ref>Wuchter et al., 2006</ref>. The second step (oxidation of nitrite into nitrate) is (mainly) done by bacteria of the genus ''[[Nitrobacter]]''. Both steps are producing energy to be coupled to ATP synthesis. Nitrifying organisms are [[chemotroph|chemoautotroph]]s, and use [[carbon dioxide]] as their [[carbon]] source for growth. Nitrification also plays an important role in the removal of [[nitrogen]] from municipal [[wastewater]]. The conventional removal is nitrification, followed by [[denitrification]]. The cost of this process resides mainly in [[aeration]] (bringing oxygen in the reactor) and the addition of an external carbon source (e.g. [[methanol]]) for the denitrification. In most environments both organisms are found together, yielding nitrate as the final product. It is possible however to design systems in which selectively nitrite is formed (the ''[[Sharon process]]''). Together with [[ammonification]], nitrification forms a [[mineralization (soil)|mineralization]] process which refers to the complete decomposition of organic material, with the release of available nitrogen compounds. This replenishes the [[nitrogen cycle]]. ==Chemistry== Nitrification is a process of nitrogen compound [[redox|oxidation]] (effectively, loss of electrons from the nitrogen atom to the oxygen atoms) : # NH<sub>3</sub> + O<sub>2</sub> → NO<sub>2</sub><sup>&minus;</sup> + 3H<sup>+</sup> + 2e<sup>&minus;</sup> # NO<sub>2</sub><sup>&minus;</sup> + H<sub>2</sub>O → NO<sub>3</sub><sup>&minus;</sup> + 2H<sup>+</sup> + 2e<sup>&minus;</sup> ==References== {{reflist}} * Treusch, A.H., Leininger, S., Kletzin, A., Schuster, S.C., Klenk, H.P., and Schleper, C. (2005) Novel genes for nitrite reductase and Amo-related proteins indicate a role of uncultivated mesophilic crenarchaeota in nitrogen cycling. Environ Microbiol 7: 1985–1995 * Purkhold, U., Pommerening-Roser, A., Juretschko, S.,Schmid, M.C., Koops, H.-P., and Wagner, M. (2000) Phylogeny of all recognized species of ammonia oxidizers based on comparative 16S rRNA and amoA sequence analysis: implications for molecular diversity surveys. Appl Environ Microbiol 66: 5368–5382 *Wuchter, C., Abbas, B., Coolen, M.J.L., Herfort, L., van Bleijswijk, J., Timmers, P., et al. (2006) Archaeal nitrification in the ocean. Proc Natl Acad Sci USA 103: 12317–12322. ==External links== * [http://www.fishdoc.co.uk/filtration/nitrification.htm Nitrification at the heart of filtration] at fishdoc.co.uk * [http://www.abdn.ac.uk/~mbi010/nitrification.htm Nitrification] at University of Aberdeen · King's College * [http://www.lagoonsonline.com/ripple.htm Nitrification Basics for Aerated Lagoon Operators] at lagoonsonline.com [[Category:Nitrogen metabolism]] [[Category:Metabolism]] [[Category:Ecology]] [[Category:Soil biology]] [[ast:Nitrificación]] [[cs:Nitrifikace]] [[de:Nitrifikation]] [[es:Nitrificación]] [[fr:Nitrification]] [[it:Nitratazione]] [[he:ניטריפיקציה]] [[lt:Nitrifikacija]] [[nl:Nitrificatie]] [[ja:硝化作用]] [[pl:Nitryfikacja]] [[ru:Нитрификация]] [[sr:Нитрификација]] [[uk:Нітрифікація]] [[zh:硝化反应]]