Methanomicrobiales

Methanomicrobiales is an order of methanogenic archaea within the class Methanomicrobia of the phylum Euryarchaeota. Members are strictly anaerobic and specialize in producing methane as part of their energy metabolism. The group comprises multiple genera and species that are commonly found in anaerobic environments and contribute to the global methane cycle.

Metabolism and physiology: Most Methanomicrobiales are hydrogenotrophic methanogens, reducing carbon dioxide with molecular hydrogen to form methane and water. Some members can use formate as an electron donor for methanogenesis. The methane formation process relies on key coenzymes, notably coenzyme M and coenzyme B, and the enzyme methyl-coenzyme M reductase (MCR) catalyzes the final step of methane production. Morphologies within the order are diverse, including rod- and spiral-shaped forms, and some members are motile while others are not.

Ecology and habitat: Methanomicrobiales are widespread in strictly anaerobic habitats such as freshwater and marine sediments, wetlands, the guts of ruminant animals and other herbivores, and anaerobic digester systems used in waste treatment and biogas production. As major methanogens, they play a significant role in methane generation in natural ecosystems and engineered processes.

Taxonomy and relevance: As a major lineage of archaeal methanogens, Methanomicrobiales is a focus of environmental microbiology, studies of the global carbon cycle, and biotechnological applications related to anaerobic digestion and biogas yield. Their diversity and activity influence methane emissions and the efficiency of methane-based bioprocesses.