Hydrogenotrophic methanogens overwrite isotope signals of subsurface methane

• 成果类型: Article
• 署名作者: Mayumi, Daisuke; Tamaki, Hideyuki; Kato, Souichiro; Igarashi, Kensuke; Lalk, Ellen; Nishikawa, Yasunori; Minagawa, Hideki; Sato, Tomoyuki; Ono, Shuhei; Kamagata, Yoichi; Sakata, Susumu
• 署名单位: National Institute of Advanced Industrial Science & Technology (AIST); National Institute of Advanced Industrial Science & Technology (AIST); National Institute of Advanced Industrial Science & Technology (AIST); Massachusetts Institute of Technology (MIT); National Institute of Advanced Industrial Science & Technology (AIST); United States Department of the Interior; United States Geological Survey
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-9146
• DOI: 10.1126/science.ado0126
• 发表日期: 2024-12-20
• 页码: 1372-1376
• 关键词: natural-waters; gen. nov.; carbon; fractionation; equilibrium; oxidation; marine; isotopologue; (ch3d)-c-13; solubility

摘要

Methane, a greenhouse gas and energy source, is commonly studied using stable isotope signals as proxies for its formation processes. In subsurface environments, methane often exhibits equilibrium isotopic signals, but the equilibration process has never been demonstrated in the laboratory. We cocultured a hydrogenotrophic methanogen with an H2-producing bacterium under conditions (55 degrees C, 10 megapascals) simulating a methane-bearing subsurface. This resulted in near-complete reversibility of methanogenesis, leading to equilibria for both hydrogen and carbon isotopes. The methanogen not only equilibrated kinetic isotope signals of initially produced methane but also modified the isotope signals of amended thermogenic methane. These findings suggest that hydrogenotrophic methanogenesis can overwrite the isotope signals of subsurface methane, distorting proxies for its origin and formation temperature-insights crucial for natural gas exploration.