Methanosarcina

Methanosarcina is a genus of methanogenic archaea in the family Methanosarcinaceae, within the phylum Euryarchaeota. Members are found in a wide range of anoxic environments, including freshwater and marine sediments, wetlands, the digestive tracts of ruminants, and anaerobic digestion reactors used for waste treatment. They can form stable aggregates or rosettes of relatively large, irregular coccoid cells.

Unlike many other archaeal methanogens, Methanosarcina species are metabolically versatile. They can produce methane by acetoclastic methanogenesis, using acetate as a substrate; they can also generate methane from CO2 and H2 (hydrogenotrophic methanogenesis) and from various methylated compounds such as methanol and methylamines (methylotrophic methanogenesis). This metabolic flexibility allows Methanosarcina to occupy acetate-rich environments where hydrogen levels are low. The methane-forming step is catalyzed by methyl-coenzyme M reductase, and the presence of the mcrA gene is a common molecular marker for these organisms.

Genomically, Methanosarcina species tend to have relatively large, well-annotated genomes and can harbor diverse pathways for energy conservation and carbon assimilation. Notable species include Methanosarcina mazei, Methanosarcina barkeri, and Methanosarcina acetivorans, which are widely studied in laboratory and biotechnological contexts.

Ecologically and industrially, Methanosarcina plays a key role in carbon cycling and biogas production, contributing to methane yields in anaerobic digesters. Research into their physiology and genetics informs strategies to optimize methane production and explore methane mitigation and bioelectrochemical applications.