Methanotrophs and methane oxidation in cold wetlands: distribution, ecology, and mechanisms

Wetlands in cold regions are significant natural sources of methane. Methane-oxidizing microbes (methanotrophs) serve as key players in mitigating methane in these ecosystems. A substantial proportion of methane, often the majority, is oxidized by aerobic methane-oxidizing bacteria (aerobic methanotrophs) before being emitted to the atmosphere. Their diversity, environmental distribution, methane oxidation capacity, and metabolic mechanisms have been intensively studied worldwide across diverse ecosystems. The relatively recent discovery of anaerobic methanotrophic archaea (ANME) and "Candidatus Methylomirabilota" (NC10 bacteria) revolutionized our understanding of methane cycling, revealing previously unrecognized anaerobic oxidation strategies, often coupled with various environmental available electron acceptors. Here, we review the role of methanotrophs in cold wetlands on a global scale, focusing on recent developments in our knowledge of their ecological distribution, methane oxidation potential, and cold-adaptation strategies. We discuss future research directions for methanotrophs in cold wetlands. Understanding the cold-adapted lifestyle of methanotrophs will necessitate combined efforts in microbiology, biochemistry, and computational biology. Harnessing the power of cold-adapted methanotrophs has the potential to significantly mitigate global warming by enhancing greenhouse gas uptake.