在这项工作中，该研究团队通过实验控制了甲烷生成的中心酶甲基辅酶M还原酶（MCR）的丰度，并测试了其细胞浓度是否会改变甲烷同位素组成。该课题组发现，在甲醇和乙酸的生长过程中，降低MCR的表达增加了甲烷和水之间氢同位素交换的程度。使用同位素支持的甲烷生成模型，研究团队发现这些变化是由于参与底物甲基氧化的酶的可逆性增加。这一结果表明，有机化合物产生的甲烷可能偏离通常假设的途径特异性同位素效应，这对解释与环境相关的甲烷强度具有重要意义。
据介绍，微生物甲烷的稳定同位素组成变化很大，其潜在的同位素存在争议。
附：英文原文
Title: Modulation of methyl–coenzyme M reductase expression alters the isotopic composition of microbial methane
Author: Jonathan Gropp, Markus Bill, Max K. Lloyd, Rebekah A. Stein, Dipti D. Nayak, Daniel A. Stolper
Issue&Volume: 2025-08-14
Abstract: The stable isotopic composition of microbial methane varies substantially, and the underlying causes are debated. In this work, we experimentally controlled the abundance of the central enzyme in methanogenesis, methyl–coenzyme M reductase (MCR), in Methanosarcina acetivorans and tested whether its cellular concentration alters methane isotopic compositions. We found that during growth on methanol and acetate, lowering the expression of mcr increases the degree of hydrogen isotope exchange between methane and water. Using an isotope-enabled model of methanogenesis, we found that these changes result from an increase in reversibility of enzymes involved in the oxidation of the substrate methyl group. This result indicates that methane produced from organic compounds can deviate from commonly assumed pathway-specific isotope effects, with implications for the interpretation of environmentally relevant methane sources.
DOI: adu2098
Source: https://www.science.org/doi/10.1126/science.adu2098