Marine microplastics enrich antibiotic resistance genes (ARGs), especially extracellular ARGs: An investigation in the East China Sea

The potential of microplastics to carry coexisting pollutants and contribute to combined pollution is a significant health concern. Here we investigate the presence of antibiotic resistance genes (ARGs) in both intracellular ARGs (iARGs) and extracellular ARGs (eARGs) forms, on microplastics collected from the coastal waters of the East China Sea. Our findings revealed that both iARGs and eARGs were enriched on microplastics. Specifically, 6- to 55-fold enrichment of iARGs was found on microplastics, while eARGs were more significantly enriched (5-140 fold). 16s rDNA analysis revealed that microplastics harbored a more diverse microbial community, particularly opportunistic pathogens, compared to surrounding seawater. This contributes to more correlations between bacterial genera and ARGs on microplastics than in sea water. Molecular ecological network analysis indicated that total nitrogen and ammonia were primary determinants of ARG and microbial enrichment on microplastics. This study provides implications for understanding the combined pollution of microplastics and ARGs.