ZnO nanorod coatings attenuate antibiotic resistance genes (ARGs) on their surface biofilms in estuarine environment

As sinks for antibiotic resistance genes (ARGs), biofilms are vital to propagate ARGs in estuarine and coastal environments. In this study, for reducing ARGs in biofilms, ZnO nanorods coatings were constructed on glass slides and placed in an estuarine environment to form biofilms. The results showed that ZnO nanorods coatings could effectively reduce the type and abundance of ARGs in biofilms, with reduction ratios of 25.1% and 37.4%, respectively. The microbial hosts, Aeromonas and Verrucomicrobia may be primarily responsible for reducing ARGs after treatment with ZnO nanorods. Additionally, ZnO nanorods can regulate ARGs through the co-resistant system (baeS/R-mdtA/B/C-acrD) by releasing zinc ions and the antioxidant system (soxR/S-acrAB-tolC) by generating reactive oxygen species. Based on structural equation modeling, ZnO nanorods can positively and indirectly induce antioxidase-related genes (AOGs) and metal resistance genes (MRGs) or indirectly negatively regulate MGEs by affecting bacterial communities, thus regulating ARGs. According to the pRDA, AOGs were found to be the dominant regulators for the variation in ARGs (27.6%), followed by MRGs (26.7%), bacterial communities (20.5%), and MGEs (17.4%). Taken together, our investigations provide a valuable method for attenuating ARGs in biofilms and further explain the mechanisms regulating ARGs.