Researchers from Nanjing University of Information Science and Technology, et al. have conducted a study entitled \u201cDepth-related variation in the activity and community structure of nitrite- and nitrate-coupled anaerobic methanotrophs in freshwater lake sediment\u201d. This study was published in Frontiers of Environmental Science & Engineering, Volume 19, Issue 8, 2025.<\/p>\n
Nitrite- and nitrate-coupled anaerobic oxidation of methane (AOM)\u2014mediated by Candidatus Methylomirabilis-like bacteria and Methanoperedens-like archaea respectively\u2014are key to freshwater carbon and nitrogen cycles, yet their vertical distribution, quantitative role in methane (CH\u2084) emission reduction, and environmental drivers in lake sediments remain unclear. To address this, the study explored vertical variation in the two AOM processes\u2019 activity and related methanotrophs\u2019 abundance, diversity, and community structure by collecting 0\u201310 cm, 10\u201320 cm, 20\u201330 cm sediment layers from four sites in Changdang Lake and conducting physicochemical analysis, \u00b9\u00b3CH\u2084 isotopic experiments, high-throughput sequencing, quantitative PCR, and statistical analyses. Data showed both AOM rates peaked in the 10\u201320 cm layer (0.41\u20133.84 nmol CH\u2084\/(g\u00b7d) for nitrite-coupled, 0.32\u20133.88 nmol CH\u2084\/(g\u00b7d) for nitrate-coupled), contributing equally to CH\u2084 consumption with a significant positive correlation; methanotroph abundance (3.34\u00d710\u2075\u20139.17\u00d710\u2076 copies\/g for Methylomirabilis-like bacteria, 1.27\u00d710\u2076\u20139.46\u00d710\u2076 copies\/g for Methanoperedens-like archaea) had no consistent vertical variation, and their community composition was stable by depth but differed across sites; sediment pH, NH\u2084\u207a, and organic carbon content were key influencing factors. This study clarifies the vertical distribution of the two AOM processes, offering insights into their role in mitigating CH\u2084 emissions and related drivers.<\/p>\n