Environmental Preferences and Functional Variations of Methanotrophs in Northeast Qinghai-Tibet Plateau Wetlands

Wetlands are important sinks of methane (CH₄), with CH₄ oxidation primarily driven by type I (Gammaproteobacteria) and type II (Alphaproteobacteria) methanotrophs. However, research on the environmental preferences of these two groups in wetlands remains limited. Here, we collected 128 samples, examined soil properties, methanotrophic abundance and community structure and potential CH₄ oxidation rates (PMORs), across both horizontal (four regions) and vertical (four soil depths) dimensions in the northeastern Qinghai-Tibet Plateau. We found that the relative abundance of type I and type II methanotrophs, methanotrophic community structure and PMORs were primarily regulated by soil ion concentration (pH and electrical conductivity). Type II methanotrophs prefer environments with low soil ion concentration and high nutrient levels (e.g., soil total organic carbon and total nitrogen), while type I methanotrophs show the opposite trend. Additionally, we found that type I and type II methanotrophs play different roles in wetlands. Type II methanotrophs, especially Methylocystis, showed higher PMORs, whereas type I methanotrophs (especially Methylobacter, Methylomonas and type Id) was crucial for maintaining methanotrophic microbial community stability as keystones. Overall, this study illustrates the disparities in the ecological roles of methanotrophs, thereby enhancing our understanding of microbially mediated carbon cycling in wetland ecosystems.