Surface-modified nanoplastics facilitate the dissemination and persistence of antibiotic resistance genes

Plastic pollution and antibiotic resistance are emerging environmental crises, which pose threat to human and ecology health. Although micro/nano plastics have been found to exacerbate antibiotic resistance genes (ARGs) dissemination, the impacts of differentially surface-modified nanoplastics on ARGs transformation remains unclear. In this study, transformation experiments were performed to elucidate the impacts of surface-modified polystyrene (PS) nanoplastics on ARGs transformation. Compared with pristine PS nanoplastics, carboxyl- and amino-modified PS nanoplastics (10 mg/L and 100 mg/L) significantly facilitate the ARG transformation frequency and efficiency. The direct mechanisms were attributed to alternations in cell membrane, including increased cell membrane permeability and pore formation on cell membrane, as well as overproduction of reactive oxygen species, which consequently induced the SOS response. And this was verified by the varied expression levels of related functional genes. Additionally, nanoplastics could inhibit the enzymatic degradation of plasmids, potentially contributing to the persistence of ARGs in environments. These findings suggest that the ecological risks associated with nanoplastics in promoting ARGs dissemination should not be overlooked, since the co-occurrence of ARGs and plastics is pervasive and persistent in diverse habitats.