Distinct methanotrophic communities exist in habitats with different soil water contents

Aerobic methane oxidizing bacteria play a key role in controlling global climate by reducing methane (CH4) emissions in natural ecosystems. We studied the community assembly processes and co-occurrence interactions of soil methanotrophs in three habitats (an alpine meadow, a marsh meadow, and a marsh) from Qinghai-Tibetan Plateau. Methanotrophic communities and CH4 oxidation potentials varied considerably between the habitats, and the diversity of methanotrophs was significantly lower in marsh meadow than in the other two soils (P < 0.001). Methanotrophic bacterial diversity was significantly correlated with soil dissolved organic carbon (DOC), pH, total carbon (TC), and total nitrogen (TN), while methanotrophic community structure was mostly correlated with soil C/N, TC, soil moisture, and TN. Stochasticity dominated methanotrophic community assembly, and increased from 67.6% in the alpine meadow and 68.0% in the marsh meadow to 98.2% in the marsh. The natural connectivity of co-occurrence network was greater in the alpine meadow than in the other two habitats, suggesting a more stable network in the alpine meadow. Methanotroph diversity contributed to the sub-network topological differences and keystone species were identified such as USCγ, Methylobacter, and RPC-1. The results suggest the existence of distinct community assembly processes and co-occurrence patterns of soil methanotrophs among different habitats, which may ultimately enhance the understanding of factors influencing CH4 oxidation rates.