Plastisphere Microbial Community and Functional Differences with Risk of Antibiotic Resistance Gene Transmission Throughout Wastewater Treatment

Wastewater treatment plants (WWTPs), which serve as a bridge between wastewater and aquatic environment, may inadvertently introduce microplastics and antibiotic resistance genes (ARGs) into receiving water. Microplastics in wastewater can accumulate microorganisms to form plastispheres, potentially increasing the risk of ARGs in WWTP effluent. To better understand this phenomenon, this study utilized metagenomics and qPCR to investigate the characteristics of microorganisms and ARGs in plastisphere and wastewater throughout the wastewater treatment process. The results showed that there were significant differences in the microbial community structure and functional expression in plastisphere and wastewater. The microbial communities in plastisphere also exhibited superior diffusion rates and greater stability. Consequently, the disinfection unit significantly reduced microbial abundance, diversity, and Human Diseases-related metabolic pathways in wastewater, yet having minimal impact on plastisphere. Additionally, the increased microbial diversity and enhanced function associated with ARG proliferation in the plastisphere elevated the relative abundance of ARGs. The presence of microplastics in WWTP protected ARGs from elimination, thereby increasing the risk of ARG being carried in effluent, and this may pose serious threats to aquatic ecosystems. These findings provide insights into the ecological risks associated with microplastics in WWTPs and emphasize the importance of comprehensively controlling microplastics entry into wastewater and enhancing microplastic removal from WWTPs.