[B-GM22_30AM2] 地球惑星科学と微生物生態学の接点

[BGM22-09] 地球微生物学が解き明かすメタン循環

*柳川 勝紀¹ (1.海洋研究開発機構)

キーワード：海底下生命圏, メタン, メタン生成, 嫌気的メタン酸化

Methane is one of the major end products of anaerobic microbial metabolism. Based on stable carbon and hydrogen isotopic compositions of methane, geochemical studies have systematically classified the origin of methane; 1) biological pathways consisting of carbon dioxide reduction coupled to molecular hydrogen oxidation and methyl-type fermentation, and 2) abiological pathways such as thermal degradation of organic matter and Fischer-Tropsch type reaction. In contrast, regarding methane consumption, recent advances in subseafloor biosphere research have unveiled the complexity of processes involved in the transformation, migration and fate of methane. Particularly, it has been recognized that marine sediments with high methane flux harbor novel lineages of microorganisms, the physiological traits of which are largely unknown due to their resistance to cultivation. Recent advances in subseafloor biosphere research indicate that microbes play much more important roles in methane production and consumption than previously assumed. Though these biogeochemical processes are not fully understood, future combined approach of geochemistry and geomicrobiology will shed light on the global methane cycle on Earth.