Methane (CH4) and nitrous oxide (N2O) are major greenhouse gases predominantly generated by microbial activities in anoxic environments. N2O inhibition of methanogenesis has been reported but comprehensive efforts to obtain kinetic information are lacking. Using the model methanogen Methanosarcina barkeri strain Fusaro and digester sludge-derived methanogenic enrichment cultures, we conducted growth yield and kinetic measurements and show that micromolar concentrations of N2O suppress growth of methanogens and CH4 production from major methanogenic substrate classes. Acetoclastic methanogenesis, estimated to account for two-thirds of the annual 1 billion metric tons of biogenic CH4, was most sensitive to N2O, with inhibitory constants (KI) in the range of 18–25 μM, followed by hydrogenotrophic (KI 60–90 μM) and methylotrophic (KI 110–130 μM) methanogenesis. Dissolved N2O concentrations exceeding these KI values are not uncommon in managed (i.e., fertilized soils, wastewater treatment plants) and unmanaged ecosystems. Future greenhouse gas emissions remain uncertain, particularly from critical zone environments (e.g., thawing permafrost) with large amounts of stored nitrogenous and carbonaceous materials that are experiencing unprecedented warming. Incorporating relevant feedback effects, such as the significant N2O inhibition on methanogenesis, can refine climate models and improve predictive capabilities.

中文翻译：

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一氧化二氮对产甲烷的抑制代表了一种被低估的温室气体排放反馈

甲烷 (CH4) 和一氧化二氮 (N2O) 是主要的温室气体，主要由缺氧环境中的微生物活动产生。N2O 抑制产甲烷作用已有报道，但缺乏获取动力学信息的综合努力。使用模型产甲烷菌 Methanosarcina barkeri 菌株 Fusaro 和消化池污泥衍生的产甲烷富集培养物，我们进行了生长产量和动力学测量，结果表明微摩尔浓度的 N2O 抑制产甲烷菌的生长和主要产甲烷底物类别的 CH4 产生。据估计，乙酰分解产甲烷作用占每年 10 亿吨生物源 CH4 的三分之二，它对 N2O 最敏感，抑制常数 (KI) 在 18–25 μM 范围内，其次是氢营养型（KI 60–90） μM) 和甲基营养型 (KI 110–130 μM) 产甲烷作用。在管理（即施肥土壤、废水处理厂）和非管理生态系统中，溶解的 N2O 浓度超过这些 KI 值的情况并不少见。未来的温室气体排放仍然不确定，特别是来自储存有大量含氮和碳质材料的关键区域环境（例如，融化的永久冻土），这些环境正在经历前所未有的变暖。纳入相关的反馈效应，例如 N2O 对产甲烷作用的显着抑制，可以完善气候模型并提高预测能力。