Anaerobic Methane Oxidation Driven by Microbial Reduction of Natural Organic Matter in a Tropical Wetland

作者：Edgardo I. Valenzuela, Alejandra Prieto‐Davó, Nguyen Esmeralda López-Lozano, Alberto Hernández-Eligio, Leticia Vega‐Alvarado, Katy Juárez, Ana Sarahí García-González, Mercedes Guadalupe López, Francisco Javier Cervantes · 发表于：Applied and Environmental Microbiology · 年份：2017 · DOI：10.1128/aem.00645-17 · 被引用次数：189 · 研究领域：Methane Hydrates and Related Phenomena、Anaerobic Digestion and Biogas Production、Hydrocarbon exploration and reservoir analysis

ABSTRACT Wetlands constitute the main natural source of methane on Earth due to their high content of natural organic matter (NOM), but key drivers, such as electron acceptors, supporting methanotrophic activities in these habitats are poorly understood. We performed anoxic incubations using freshly collected sediment, along with water samples harvested from a tropical wetland, amended with 13 C-methane (0.67 atm) to test the capacity of its microbial community to perform anaerobic oxidation of methane (AOM) linked to the reduction of the humic fraction of its NOM. Collected evidence demonstrates that electron-accepting functional groups (e.g., quinones) present in NOM fueled AOM by serving as a terminal electron acceptor. Indeed, while sulfate reduction was the predominant process, accounting for up to 42.5% of the AOM activities, the microbial reduction of NOM concomitantly occurred. Furthermore, enrichment of wetland sediment with external NOM provided a complementary electron-accepting capacity, of which reduction accounted for ∼100 nmol 13 CH 4 oxidized · cm −3 · day −1 . Spectroscopic evidence showed that quinone moieties were heterogeneously distributed in the wetland sediment, and their reduction occurred during the course of AOM. Moreover, an enrichment derived from wetland sediments performing AOM linked to NOM reduction stoichiometrically oxidized methane coupled to the reduction of the humic analogue anthraquinone-2,6-disulfonate. Microbial populations potentially...