Editing Methanogen (section)

{{short description|Type of microorganism that produces methane as a waste product}}
{{Distinguish|Methanotroph}}
'''Methanogens''' are anaerobic [[archaea]] that produce [[methane]] as a byproduct of their energy [[metabolism]], i.e., [[catabolism]]. Methane production, or [[methanogenesis]], is the only [[biochemical pathway]] for [[Adenosine triphosphate|ATP]] generation in methanogens. All known methanogens belong exclusively to the [[Domain (biology)|domain]] Archaea, although some [[bacteria]], [[plant]]s, and [[animal]] cells are also known to produce methane.<ref>{{Cite journal |last1=Ernst |first1=Leonard |last2=Steinfeld |first2=Benedikt |last3=Barayeu |first3=Uladzimir |last4=Klintzsch |first4=Thomas |last5=Kurth |first5=Markus |last6=Grimm |first6=Dirk |last7=Dick |first7=Tobias P. |last8=Rebelein |first8=Johannes G. |last9=Bischofs |first9=Ilka B. |last10=Keppler |first10=Frank |date=2022-03-17 |title=Methane formation driven by reactive oxygen species across all living organisms |url=https://www.nature.com/articles/s41586-022-04511-9 |journal=Nature |language=en |volume=603 |issue=7901 |pages=482–487 |doi=10.1038/s41586-022-04511-9 |pmid=35264795 |bibcode=2022Natur.603..482E |issn=0028-0836}}</ref> However, the biochemical pathway for methane production in these organisms differs from that in methanogens and does not contribute to ATP formation. Methanogens belong to various [[Phylum|phyla]] within the domain Archaea. Previous studies placed all known methanogens into the superphylum Euryarchaeota.<ref>{{Cite journal |last1=Liu |first1=Yuchen |last2=Whitman |first2=William B. |date=March 2008 |title=Metabolic, Phylogenetic, and Ecological Diversity of the Methanogenic Archaea |url=https://nyaspubs.onlinelibrary.wiley.com/doi/10.1196/annals.1419.019 |journal=Annals of the New York Academy of Sciences |language=en |volume=1125 |issue=1 |pages=171–189 |doi=10.1196/annals.1419.019 |pmid=18378594 |bibcode=2008NYASA1125..171L |issn=0077-8923|url-access=subscription }}</ref><ref name=":0" /> However, recent phylogenomic data have led to their reclassification into several different phyla.<ref name=":1">{{cite web |title=Archived copy |url=http://spacecenter.uark.edu/JillJabstract.doc |url-status=dead |archive-url=https://web.archive.org/web/20090327135553/http://spacecenter.uark.edu/JillJabstract.doc |archive-date=2009-03-27 |access-date=2009-09-20}}</ref> Methanogens are common in various anoxic environments, such as marine and freshwater sediments, [[wetland]]s, the [[Gastrointestinal tract|digestive tract]]s of animals, [[wastewater treatment]] plants, [[Paddy field|rice paddy]] soil, and [[landfill]]s.<ref name=":2" /> While some methanogens are [[extremophile]]s, such as ''[[Methanopyrus|Methanopyrus kandleri]]'', which grows between 84 and 110°C,<ref name=":3" /> or ''Methanonatronarchaeum thermophilum'', which grows at a pH range of 8.2 to 10.2 and a {{chem2|Na+}} concentration of 3 to 4.8 M,<ref name=":4" /> most of the isolates are [[Mesophile|mesophilic]] and grow around neutral pH.<ref name=":5" />