Methanogen
Methanopyrus kandleri
- Methanobacteria
- Methanococci
- Methanomicrobia
(Selection)
- Methanobacteriales
- Methanomicrobiales
- Methanopyrales
- Methanococcales
- Methanosarcinales
- Methanocellales
As methane producers or methanogens ( formerly known as methanogens ) are archaea ( Archaea) referred in their energy metabolism takes place methane formation.
Taxonomy
The methanogens are grouped in classes Methanobacteria, Methanococci and Methanomicrobia, which include six orders. The methane-forming microorganisms are often incorrectly referred to as bacteria or methanogens. Originally bacteria and archaea a common taxonomic group ( taxon ) have been assigned. Since the early 1990s molecular biological methods are available that allowed a correct phylogenetic classification and led to the realization that bacteria and archaea, two different taxa. The ability to methanogenesis is found exclusively in the archaea. Types of orders Methanobacteriales, Methanococcales, Methanomicrobiales, Methanocellales, Methanosarcinales and Methanopyrales known as methanogens. They all belong to the Department of Euryarchaeota.
Physiology, ecology
The methane producers ( methanogens ) use the exergonic (energy releasing ) methanogenesis as an energy source. Some methanogens are autotrophic wasserstoffoxidierende. They use carbon dioxide ( CO2) as the sole carbon source in the synthesis of all the cellular components ( anabolism). You assimilate CO2 on the acetyl- CoA pathway.
A distinction acetatspaltende methanogens and H2 -oxidizing methanogens. Acetatspaltende methanogens can form methane from methyl-containing compounds by cleave the methyl group and to reduce methane. You own the coenzyme required for this Methanophenazin. Among them is the genus Methanosarcina. H2 -oxidizing methanogens form methane by reduction of CO2 with hydrogen to methane and water as well as by the reaction of formic acid ( HCOOH ); they have no Methanophenazin. They include the genera Methanococcus, Methanobacterium and Methanopyrus.
The methanogens are strictly anaerobic, they metabolize at temperatures between 0 and 70 ° C, a few species even up to 90 ° C, at higher temperatures they are killed. Elevated temperatures increase the efficiency of methanogens. You need to anoxic, pH-neutral or slightly alkaline environment with at least 50% water. The anoxic aquatic sediments, water-saturated or over- accumulated soil (eg Moore and rice fields), dung, manure and digestive tract of ruminants are particularly good habitats for methanogens, can be found here for her important nitrogen compounds, minerals and trace elements. Inhibitors of methanogens are organic acids, disinfectants and oxygen.
Other habitats of methanogens are the large intestine of vertebrates, the digestive tract of termites, as well as the digester of wastewater treatment and biogas plants.
The methanogens are at the last position of the anaerobic food chain, occur in the various conversion processes. At the end is formed by the activity of methanogens methane.