Metagenomic analysis reveals the composition and sources of antibiotic resistance genes in coastal water ecosystems of the Yellow Sea and Yangtze River Delta

The rapid development of coastal areas has raised concerns about marine environmental pollution. In this study, metagenomics was employed to investigate antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and bacterial communities in the Yellow Sea and Yangtze River Delta in China. Multidrug resistance genes were the most abundant ARGs in these regions. Transposons and insertion_element_IS91 were the dominant MGEs, closely related to the horizontal gene transfer of ARGs. Temperature, dissolved oxygen, pH, and depth were identified as important environmental factors influencing the distribution of ARGs in seawater. Oil, agriculture, animal husbandry, and wastewater treatment plants are likely the primary sources of ARGs. From the perspective of ARG control, bacterial communities contributed the most to the development of the resistome and may carry ARGs, spreading from the Yangtze River Delta to the Yellow Sea along ocean currents. A comparison with Tara Oceans datasets revealed that the dominant ARG types and bacterial genera in coastal waters were consistent with global characteristics, with variations in ARG subtypes. This study expands knowledge on the distribution patterns of ARGs at an offshore scale and provides a reference for the prevention and control of resistant gene pollution in the Yellow Sea and Yangtze River Delta.