Pathways and Risks of Antibiotic Resistance Genes Along a Rural to Urban River Gradient

ABSTRACT Antibiotic resistance genes (ARGs) are emerging environmental contaminants that pose significant risks to public and ecosystem health. This study investigated the distribution of ARGs and their associations with carbon (C), nitrogen (N), and phosphorus (P) cycling in sediments along a rural to urban gradient of the Liangtan River, China, using high‐throughput metagenomic sequencing. We detected 327 ARG subtypes, with the highest diversity and abundance in urban and industrial areas. Sulfonamide, tetracycline, and rifamycin resistance genes were predominant, primarily mediated by antibiotic efflux mechanisms. Microbial community structure varied significantly along the gradient, with Proteobacteria dominating all sites. Correlation analysis revealed significant associations between the Simpson index of microbial diversity and specific ARGs ( MuxB , floR ), as well as negative correlations between total organic carbon (TOC) and certain ARGs ( MexK , lnuF , EreA2 ). Co‐occurrence network analysis identified four microbial ecological clusters (MOD1–MOD4), among which MOD2 was strongly correlated with TOC and total nitrogen. Importantly, ARGs were significantly linked to nutrient cycling pathways, especially in agricultural regions, suggesting co‐regulation of resistance and metabolic functions. These findings highlight the role of nutrient pollution in shaping ARG propagation and provide new insights into microbial adaptation mechanisms in anthropogenically impacted river systems.