Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. They are common in wetlands, where they are responsible for marsh gas, and in the guts of animals such as ruminants and humans, where they are responsible for the methane content of flatulence.^{[citation needed]} In marine sediments biomethanation is generally confined to where sulfates are depleted, below the top layers.^[1] Others are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the "solid" rock of the earth's crust, kilometers below the surface. There are over 50 described species of methanogens, which are paraphyletic and all included among the Euryarchaeota. Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Methane is a chemical compound with the molecular formula CH4. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... A subtropical wetland in Florida, USA, with an endangered American Crocodile. ... Natural gas rig Natural gas is a gas produced by the anaerobic decay of organic material. ... It has been suggested that this article or section be merged with Ruminantia. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Flatulence (expelled through the anus in a process commonly known as farting or emitting gas) is the presence of a mixture of gases known as flatus in the digestive tract of mammals. ... Marine is an umbrella term for things relating to the ocean, as with marine biology, marine geology, and as a term for a navy, etc. ... This article or section cites very few or no references or sources. ... Biomethanation is the process of conversion of organic matter in the waste (liquid or solid) to BioMethane (sometimes referred to as BioGas) and manure by microbial action in the absence of air, known as anaerobic digestion. Category: ... In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ... An extremophile is an organism, usually unicellular, which thrives in or requires extreme conditions that would exceed optimal conditions for growth and reproduction in the majority of mesophilic terrestrial organisms. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57 F or... Hydrothermal vents are fissures in a planets surface from which geothermally heated water issues. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... Classes Archaeoglobi Halobacteria Methanobacteria Methanococci Methanomicrobia Methanopyri Thermococci Thermoplasmata The Euryarchaeota are a major group of Archaea. ...

Methanogens are anaerobic. Most methanogens are rapidly killed by the presence of oxygen. An exception is Methanosarcina barkeri, which contains a superoxide dismutase (SOD) enzyme and may survive longer.^[2] Some, called hydrogenotrophic, use carbon dioxide (CO₂) as a source of carbon, and hydrogen as a reducing agent. Some of the CO₂ is reacted with the hydrogen to produce methane, which produces an electrochemical gradient across a membrane, used to generate ATP through chemiosmosis. In contrast, plants and algae use water as their reducing agent. Aerobic and anaerobic bacteria can be identified by growning them in liquid culture: 1: Obligate aerobic bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen. ... Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... In cellular biology, an electrochemical gradient refers to the electrical and chemical properties across a membrane. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Chemiosmosis is the diffusion of ions across a membrane. ...

Although most marine biogenic methane is the result of CO₂ reduction, a small amount is derived from acetate (CH₃COO^-).^[3] Archaea that catabolize this for energy are referred to as acetotrophic or aceticlastic. Methylotrophic archaea utilize methylated compounds such as methylamines, methanol, and methanethiol as well. An acetate, or ethanoate, is a salt or ester of acetic acid. ... Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy. ... Methylamine is a simple primary amine with a formula of CH3NH2. ... Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naptha or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... Methanethiol (also known as methyl mercaptan) is a colorless gas with a smell like rotten cabbage. ...

Ecologically, methanogens play the vital role in anaerobic environments of removing excess hydrogen and fermentation products that have been produced by other forms of anaerobic respiration. Methanogens typically thrive in environments in which all other electron acceptors (such as oxygen, nitrate, sulfate, and trivalent iron) have been depleted. In the deep rock they obtain their hydrogen from the thermal and radioactive breakdown of water. Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Trinitrate redirects here. ... In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ...

Methanogens have been found in several extreme environments on Earth - buried under kilometres of ice in Greenland and living in hot, dry desert soil. They are known to be the most common prokaryotes archaebacteria in deep subteranean habitats. Prokaryotes are unicellular (in rare cases, multicellular) organisms without a nucleus. ...

Live microbes making methane were found in a glacial ice core sample retrieved from three kilometres under Greenland by researchers from the University of California, Berkeley, US.^[4]

Another study^[5] has also discovered methanogens in a harsh environment on Earth. Researchers studied dozens of soil and vapour samples from five different desert environments in Utah, Idaho and California in the US, and in Canada and Chile. Of these, five soil samples and three vapour samples from the vicinity of the Mars Desert Research Station in Utah were found to have signs of viable methanogens.^[6]

Some scientists have proposed that the presence of methane in the Martian atmosphere may be indicative of native methanogens on that planet.^[7] Adjectives: Martian Atmosphere Surface pressure: 0. ...

Closely related to the methanogens are the anaerobic methane oxidizers, which utilize methane as a substrate in conjunction with the reduction of sulfate and nitrate.^[8]

References

1. ^ J.K. Kristjansson, et al. (1982). "Different Ks values for hydrogen of methanogenic bacteria and sulfate-reducing bacteria: an explanation for the apparent inhibition of methanogenesis by sulfate". Arch. Microbiol. 131: 278-282. 
2. ^ http://spacecenter.uark.edu/JillJabstract.doc
3. ^ M.J. Whiticar, et al. (1986). "Biogenic methane formation in marine and freshwater environments: CO₂ reduction vs. acetate fermentation — isotope evidence". Geochim. Cosmochim. Acta 50: 393-709. 
4. ^ Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0507601102)
5. ^ Icarus (vol. 178, p. 277)cs:Methanogen
6. ^ Extreme bugs back idea of life on Mars
7. ^ Crater Critters: Where Mars Microbes Might Lurk
8. ^ Thauer, R. K. and Shima, S., "Biogeochemistry: Methane and microbes", Nature, 2006, 440, 878-879