Denitrification is the process of reducing nitrate and nitrite, highly oxidised forms of nitrogen available for consumption by a many groups of organisms, into gaseous nitrogen, which is far less accessible to life forms but makes up the bulk of our atmosphere. It can be thought of as the opposite of nitrogen fixation, which converts gaseous nitrogen into a more biologically available form. The process is performed by heterotrophic bacteria (such as Paracoccus denitrificans, Thiobacillus denitrificans, and various pseudomonads) from all main proteolytic groups. Denitrification and nitrification are parts of the nitrogen cycle. Semi-accurate illustration of a redox reaction Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... An electrostatic potential map of the nitrate ion. ... // Definition The nitrite ion is NO2−. A nitrite compound is one that contains this group, either an ionic compound, or an analogous covalent one. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Atomic mass 14. ... Layers of Atmosphere (NOAA) Air redirects here. ... A heterotroph (Greek heteron = (an)other and trophe = nutrition) is an organism that requires organic substrates to get its carbon for growth and development. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Binomial name Paracoccus denitrificans Davis, 1969 Paracoccus denitrificans, a Gram-negative, coccoid, hydrogen-oxidizing bacterium, formerly known as Micrococcus denitrificans, was first isolated in 1910 by Martinus Beijerinck [1]. It was renamed in 1969 to Paracoccus denitrificans by Davis [2]. Paracoccus denitrificans harbors many features also found in mitochondria and... Nitrogen cycle Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. ... Schematic representation of the flow of Nitrogen through the environment. ...

Denitrification takes place under special conditions in both terrestrial and marine ecosystems. In general, it occurs when oxygen (which is a more favourable electron acceptor) is depleted, and bacteria turn to nitrate in order to respire organic matter. Because our atmosphere is rich with oxygen, denitrification only takes place in some soils and groundwater, wetlands, poorly ventilated corners of the ocean, and in seafloor sediments. An ecosystem, a contraction of ecological and system, refers to the collection of biotic and abiotic components and processes that comprise and govern the behavior of some defined subset of the biosphere. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... Organic has several meanings and related topics. ... Loess field in Germany For the Alternative Metal band, see SOiL. Soil, comprising the pedosphere, is positioned at the interface of the lithosphere with the atmosphere, and hydrosphere. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... A subtropical wetland in Florida, USA, with an endangered American Crocodile. ...

Denitrification proceeds through some combination of the following steps:

nitrate → nitrite → nitric oxide → nitrous oxide → dinitrogen gas

Or expressed as a redox reaction: An electrostatic potential map of the nitrate ion. ... // Definition The nitrite ion is NO2−. A nitrite compound is one that contains this group, either an ionic compound, or an analogous covalent one. ... R-phrases , , , , S-phrases , , , Supplementary data page Structure and properties n, εr, etc. ... R-phrases S-phrases Supplementary data page Structure and properties n, εr, etc. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Atomic mass 14. ... Semi-accurate illustration of a redox reaction Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ...

2NO₃^- + 10e^- + 12H⁺ → N₂ + 6H₂O

Denitrification is the second step in the nitrification-denitrification process, the conventional way to remove nitrogen from sewage and municipal wastewater. It is also an instrumental process in riparian zones for the removal of excess nitrate from groundwater contaminated by fertiliser use. Sewage is the liquid water produced by human society which typically contains washing water, laundry waste, faeces, urine and other liquid or semi-liquid wastes. ... Wastewater is any water that has been adversely affected in quality by anthropogenic influence. ... A riparian zone schematic from the Everglades. ...

Direct reduction from nitrate to ammonium (a process known as dissimilatory nitrate reduction to ammonium or DNRA) is also possible for organisms that have the nrf-gene. This is less common than denitrification in most ecosystems as a means of nitrate reduction. A ball-and-stick model of the ammonium cation Fumes from hydrochloric acid and ammonia forming a white cloud of ammonium chloride Ammonium is also an old name for the Siwa Oasis in western Egypt. ... For other meanings of this term, see gene (disambiguation). ...

Reduction under anoxic conditions can also occur through process called anaerobic ammonia oxidation (Anammox), this reaction is expressed as the following: Anammox -acronym for anaerobic ammonium oxidation- is the latest addition to the knowledge on the nitrogen cycle. ...

NH₄⁺ + 2NO₃^- → N₂ + 2H₂O

In some wastewater treatment plants, small amounts of methanol is added to the wastewater to provide a carbon source for the denitrification bacteria. Also called Wastewater treatment works Sewage treatment – treatment and disposal of human waste. ...

Literature

Zumft, W.G. (1997): Cell biology and molecular basis of denitrification. In: Microbiol. Mol. Biol. Rev. Bd. 61, Nr. 4, S. 533-616. PMID 9409151 PDF

See also

• anaerobic respiration
• bioremediation
• sewage treatment
• wetland
• anammox