Evidence for the connectivity of antibiotic resistance genes between seamount and coastal environments

Antibiotic resistance genes (ARGs) have drawn global attention and are ubiquitously detected in marine environments. Seamounts, prominent seafloor features with high biodiversity, may be hotspots for ARG proliferation and transfer. However, little is known about the existence, microbial associations, or connectivity with terrestrial sources of ARGs in seamounts. In this study, high-throughput sequencing approaches were employed to investigate the distribution, hosts, mobility, and coastal connectivity of ARGs in sediments from the Zhongnan Seamount, South China Sea. The most abundant ARG types were elfamycin, aminoglycoside, and tetracycline. ARG abundance was significantly higher in abyssopelagic zone sediments, suggesting the seamount acts as a sink and deep-sea regions are a major ARG reservoir. Results indicated high horizontal gene transfer potential, with key genes EF-Tu, rpsJ, parC, and parE as predominant mediators. Metagenome-assembled genomes identified 36 bacterial genera as ARG hosts, dominated by Methylomirabilota and Pseudomonadota. The source tracking and genetic connectivity analysis revealed a clear input of coastal ARGs to the seamount, emphasizing the need to investigate global ARG dissemination and its potential ecological effects. Overall, these findings identify the seamount environment as a deep-sea ARG hotspot, providing valuable insights into the prevalence, hosts, and sources of ARGs in the marine ecosystem.