Community Structure and Function of Aerobic Methanotrophs in Urban River Sediments: A Case Study of the Jialing River

Rivers are hotspots of global methane emission and oxidation, yet research on aerobic methanotrophy in urban river sediments remains limited. Here, we collected sediments of the Jialing River and its tributary (Xixi River) from the urban area of Nanchong City (Sichuan Province, China), and used microcosm incubation and high-throughput sequencing methods to investigate the aerobic methane oxidation rate and the community structure of methanotrophs of these urban river sediments. Our results indicated that these urban river sediments exhibited substantial methane oxidation potential, with the maximum rate observed at the downstream site; high-throughput sequencing revealed that type I methanotrophs (Methylobacter, Methylomicrobium and Crenothrix) were the key microbial groups responsible for aerobic methane oxidation. The river physico-chemical properties such as dissolved organic carbon (DOC), total carbon (TC) and C/N ratio correlated significantly with aerobic methane oxidation rates. These findings suggest that urban rivers possess significant methane oxidation potential, which is notably affected by carbon and nitrogen contents. Future research should focus on the metabolic mechanisms of urbanisation on fluvial methanotrophy.