Department of Microbiology, University of Georgia, Athens, GA 30602, USA.
Department of Microbiology, University of Georgia, Athens, GA 30602, USA.
Curr Biol. 2018 Jul 9;28(13):R727-R732. doi: 10.1016/j.cub.2018.05.021.
Methanogenesis is an anaerobic respiration that generates methane as the final product of metabolism. In aerobic respiration, organic matter such as glucose is oxidized to CO, and O is reduced to HO. In contrast, during hydrogenotrophic methanogenesis, H is oxidized to H, and CO is reduced to CH. Although similar in principle to other types of respiration, methanogenesis has some distinctive features: the energy yield is very low, ≤1 ATP per methane generated, and only methanogens - organisms capable of this specialized metabolism - carry out biological methane production. Methanogens, like the process they catalyze, are similarly distinctive. Methanogens are comprised exclusively of archaea. They are obligate methane producers, that is, they do not grow using fermentation or alternative electron acceptors for respiration. Finally, methanogens are strict anaerobes and do not grow in the presence of O. Historically, methanogenesis has been viewed as a highly specialized metabolism restricted to a narrow group of prokaryotes. However, recent developments have revealed enormous diversity within the methanogens and suggest that this metabolism is one of the most ancient on earth.
产甲烷作用是一种无氧呼吸，其代谢的最终产物是甲烷。在有氧呼吸中，葡萄糖等有机物质被氧化为 CO，而 O 被还原为 HO。相比之下，在氢营养型产甲烷作用中，H 被氧化为 H，而 CO 被还原为 CH。虽然产甲烷作用在原理上与其他类型的呼吸作用相似，但它具有一些独特的特征：产能量非常低，每生成一个甲烷分子仅产生 1 个 ATP，并且只有能够进行这种特殊代谢的产甲烷菌——能够进行生物甲烷生成的生物体——才能进行生物甲烷生成。产甲烷菌及其所催化的过程同样具有独特性。产甲烷菌完全由古菌组成。它们是专性产甲烷菌，也就是说，它们不能通过发酵或替代电子受体进行呼吸来生长。最后，产甲烷菌是严格的厌氧菌，在存在 O 的情况下无法生长。历史上，产甲烷作用被视为一种高度专业化的代谢作用，仅限于少数几种原核生物。然而，最近的发展揭示了产甲烷菌内部存在巨大的多样性，并表明这种代谢作用是地球上最古老的代谢作用之一。
