Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16801, USA.
Sci Adv. 2019 Aug 21;5(8):eaaw9059. doi: 10.1126/sciadv.aaw9059. eCollection 2019 Aug.
Although two-thirds of the nearly 1 billion metric tons of methane produced annually in Earth's biosphere derives from acetate, the in situ process has escaped rigorous understanding. The unresolved question concerns the mechanism by which the exceptionally marginal amount of available energy supports acetotrophic growth of methanogenic archaea in the environment. Here, we show that conserves energy by Fe(III)-dependent respiratory metabolism of acetate, augmenting production of the greenhouse gas methane. An extensively revised, ecologically relevant, biochemical pathway for acetotrophic growth is presented, in which the conservation of respiratory energy is maximized by electron bifurcation, a previously unknown mechanism of biological energy coupling. The results transform the ecological and biochemical understanding of methanogenesis and the role of iron in the mineralization of organic matter in anaerobic environments.
尽管地球生物圈每年产生的近 10 亿吨甲烷中，有三分之二来自乙酸盐，但这一原位过程仍未得到严格的理解。悬而未决的问题是，可用能量极其微薄，如何支持环境中乙酸营养型产甲烷古菌的生长。在这里，我们表明，通过依赖 Fe(III)的乙酸呼吸代谢来 ，从而增强温室气体甲烷的生成。提出了一个经过广泛修订的、生态上相关的、产乙酸的生化途径，其中电子分支（一种以前未知的生物能量耦合机制）最大化了呼吸能量的保护。研究结果改变了对产甲烷作用以及铁在厌氧环境中有机物矿化过程中作用的生态和生化理解。
