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Anammox, an abbreviation for ANaerobic AMMonium OXidation, is a globally important microbial process of the nitrogen cycle.〔Arrigo, R. A. Marine microorganisms and global nutrient cycles. Nature 437, 349–355 (2005)〕 The bacteria mediating this process were identified in 1999, and at the time were a great surprise for the scientific community.〔Strous, M. et al. Missing lithotroph identified as new planctomycete. Nature 400, 446–449 (1999)〕 It takes place in many natural environments and anammox is also the trademarked name for the anammox-based ammonium removal technology that was developed〔Jetten Michael Silvester Maria, Van Loosdrecht Marinus Corneli; Technische Universiteit Delft, (patent WO9807664 )〕 by the Delft University of Technology. ==Process background== In this biological process, nitrite and ammonium are converted directly into dinitrogen gas.〔 〕 :NH4+ + NO2− → N2 + 2H2O. Globally, this process may be responsible for 30-50% of the dinitrogen gas produced in the oceans.〔Devol, A. H. et al. Nitrogen cycle: solution to a marine mystery. Nature 422(6932), 575-576 (2003)〕 It is thus a major sink for fixed nitrogen and so limits oceanic primary productivity. The bacteria that perform the anammox process belong to the bacterial phylum Planctomycetes. Currently, five anammox genera have been discovered: ''Brocadia'', ''Kuenenia'', ''Anammoxoglobus'', ''Jettenia'' (all fresh water species), and ''Scalindua'' (marine species).〔Jetten, M. S. M. et al. Biochemistry and molecular biology of anammox bacteria. Critical Reviews in Biochemistry and Molecular Biology 44(2-3), 65-84 (2009)〕 The anammox bacteria are characterized by several striking properties: they all possess one anammoxosome, a membrane bound compartment inside the cytoplasm which is the locus of anammox catabolism. Further, the membranes of these bacteria mainly consist of ladderane lipids so far unique in biology.〔Boumann H. A. et al. Biophysical properties of membrane lipids of anammox bacteria: I. Ladderane phospholipids form highly organized fluid membranes. Biochim Biophys Acta 1788(7), 1444-1451 (2009)〕 Of special interest is the conversion to hydrazine (normally used as a high-energy rocket fuel, and poisonous to most living organisms) as an intermediate.〔 〕 A final striking feature of the organism is the extremely slow growth rate. The doubling time is anywhere from 7–22 days.〔Kartal, B. et al. How to make a living from anaerobic ammonium oxidation. FEMS Microbiology Reviews 37, 428-461 (2013)〕 The anammox bacteria are geared towards converting their substrates at very low concentrations; in other words, they have a very high affinity to their substrates ammonium and nitrite (sub-micromolar range).〔〔Yan J, Haaijer SCM, Op den Camp HJM, van Niftrik L, Stahl DA, Ko ̈nneke M, Rush D, Sinninghe Damste ́ JS, Hu YY, Jetten MSM (2012) Mimicking the oxygen minimum zones: stimulating interaction of aerobic archaeal and anaerobic bacterial ammonia oxidizers in a laboratory- scale model system. Environ Microbiol 14:3146–3158〕 Anammox cells are packed with cytochrome c type proteins (~30% of the protein complement), including the enzymes that perform the key catabolic reactions of the anammox process, making the cells remarkably red. The anammox process was originally found to occur only from 20 °C to 43 °C〔 Strous, M., Kuenen, J.G., Jetten, M.S. 1999. Key Physiology of Anaerobic Ammonium Oxidation. App. Environ. Microb. (3248-3250)〕 but more recently, anammox has been observed at temperatures from 36 °C to 52 °C in hot springs〔 Jaeschke et al. 2009. 16s rRNA gene and lipid biomarker evidence for anaerobic ammonium-oxidizing bacteria (anammox) in California and Nevada hot springs. FEMS Microbiol. Ecol. 343-350〕 and 60 °C to 85 °C at hydrothermal vents located along the Mid-Atlantic Ridge.〔Byrne, N., Strous, M., Crepeau, V, et al. 2008. Presence and activity of anaerobic ammonium-oxidizing bacteria at deep-sea hydrothermal vents. The ISME Journal.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Anammox」の詳細全文を読む スポンサード リンク
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