Editing Methanogen (section)

=== Methanogens in the digestive tract of animals ===
The digestive tract of animals is characterized by a nutrient-rich and predominantly anaerobic environment, making it an ideal habitat for many microbes, including methanogens. Despite this, methanogens and archaea, in general, were largely overlooked as part of the gut microbiota until recently. However, they play a crucial role in maintaining gut balance by utilizing end products of bacterial fermentation, such as H<sub>2</sub>, acetate, methanol, and methylamines.{{cn|date=March 2025}}

[[Methanobrevibacter smithii]] is the predominant methanogenic archaeon in the [[microbiota]] of the [[gastrointestinal tract|human gut]].<ref>{{cite Q|Q54521537}}</ref> Recent extensive surveys of archaea presence in the animal gut, based on 16S rRNA analysis, have provided a comprehensive view of archaea diversity and abundance.<ref>{{Cite journal |last1=Youngblut |first1=Nicholas D. |last2=Reischer |first2=Georg H. |last3=Dauser |first3=Silke |last4=Maisch |first4=Sophie |last5=Walzer |first5=Chris |last6=Stalder |first6=Gabrielle |last7=Farnleitner |first7=Andreas H. |last8=Ley |first8=Ruth E. |date=2021-10-26 |title=Vertebrate host phylogeny influences gut archaeal diversity |journal=Nature Microbiology |language=en |volume=6 |issue=11 |pages=1443–1454 |doi=10.1038/s41564-021-00980-2 |issn=2058-5276 |pmc=8556154 |pmid=34702978}}</ref><ref>{{Cite journal |last1=Thomas |first1=Courtney M. |last2=Desmond-Le Quéméner |first2=Elie |last3=Gribaldo |first3=Simonetta |last4=Borrel |first4=Guillaume |date=2022-06-10 |title=Factors shaping the abundance and diversity of the gut archaeome across the animal kingdom |journal=Nature Communications |language=en |volume=13 |issue=1 |page=3358 |doi=10.1038/s41467-022-31038-4 |issn=2041-1723 |pmc=9187648 |pmid=35688919|bibcode=2022NatCo..13.3358T }}</ref><ref>{{Cite journal |last1=Protasov |first1=Evgenii |last2=Nonoh |first2=James O. |last3=Kästle Silva |first3=Joana M. |last4=Mies |first4=Undine S. |last5=Hervé |first5=Vincent |last6=Dietrich |first6=Carsten |last7=Lang |first7=Kristina |last8=Mikulski |first8=Lena |last9=Platt |first9=Katja |last10=Poehlein |first10=Anja |last11=Köhler-Ramm |first11=Tim |last12=Miambi |first12=Edouard |last13=Boga |first13=Hamadi I. |last14=Feldewert |first14=Christopher |last15=Ngugi |first15=David K. |date=2023-11-15 |title=Diversity and taxonomic revision of methanogens and other archaea in the intestinal tract of terrestrial arthropods |journal=Frontiers in Microbiology |volume=14 |doi=10.3389/fmicb.2023.1281628 |doi-access=free |issn=1664-302X |pmc=10684969 |pmid=38033561}}</ref> These studies revealed that only a few archaeal lineages are present, with the majority being methanogens, while non-methanogenic archaea are rare and not abundant. Taxonomic classification of archaeal diversity identified that representatives of only three phyla are present in the digestive tracts of animals: Methanobacteriota (order Methanobacteriales), Thermoplasmatota (order Methanomassiliicoccales), and Halobacteriota (orders Methanomicrobiales and Methanosarcinales). However, not all families and genera within these orders were detected in animal guts, but only a few genera, suggesting their specific adaptations to the gut environment.{{cn|date=March 2025}}