据悉，甲烷是一种温室气体和能量源，通常以稳定同位素信号作为其形成过程的代用物进行研究。在地下环境中，甲烷经常表现出平衡同位素信号，但平衡过程从未在实验室中得到证实。
研究团队在模拟含甲烷地下环境的条件下（55°C， 10兆帕斯卡），将一种氢营养型甲烷菌与一种产氢细菌共培养。这导致甲烷生成几乎完全可逆，导致氢和碳同位素平衡。
产甲烷菌不仅平衡了初始产甲烷的动力学同位素信号，而且修饰了修正后的热成因甲烷的同位素信号。
这些发现表明，氢营养甲烷生成可以覆盖地下甲烷的同位素信号，扭曲其来源和地层温度的代用指标，而这些指标对天然气勘探至关重要。
附：英文原文
Title: Hydrogenotrophic methanogens overwrite isotope signals of subsurface methane
Author: Daisuke Mayumi, Hideyuki Tamaki, Souichiro Kato, Kensuke Igarashi, Ellen Lalk, Yasunori Nishikawa, Hideki Minagawa, Tomoyuki Sato, Shuhei Ono, Yoichi Kamagata, Susumu Sakata
Issue&Volume: 2024-12-20
Abstract: 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°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.
DOI: ado0126
Source:https://www.science.org/doi/10.1126/science.ado0126