PET hydrolase mitigated the accumulation of antibiotic resistance genes in plastisphere during high temperature sludge composting

Environmental polyethylene terephthalate microplastics (PET-MPs) provide persistent surfaces for microbial colonization and promote the spread of antibiotic resistance genes (ARGs). We have previously shown that PET hydrolase (WCCG) can effectively decompose PET-MPs in high temperature sludge composting, but whether and how ARGs respond to the enzyme additive remains unknown. Here we tested the performance of WCCG on the degradation of PET-MPs, microbial communities and ARGs using high-throughput sequencing and qPCR in 220 L sludge composters. Our results show that, while composting can markedly reduce ARGs in control, the addition of PET-MPs increased ARGs and intI1 by 262.3 % and 747.0 % as compared to control on day 50, respectively. Surprisingly, the plastisphere served as a persistent hotspot, with ARGs abundance up to 32-fold higher than compost samples, particularly for tetG and ermF. The addition of WCCG reduced ARGs by 38.93 % in compost and 26.99 % in the plastisphere on day 50 of composting. ARG abundance was significantly positively correlated with pathogenic genera including Psychrobacter, Erysipelothrix, and Clostridium. Through resistance screening, we isolated Psychrobacter griseus and confirmed that it hosted a specific ARG (tetG). WCCG reshaped the accumulation pathways associated with tetG within the plastisphere, attenuating the positive correlation between the genus Psychrobacter and tetG abundance. These findings highlight enzymatic PET degradation as a potential strategy to simultaneously reduce microplastic pollution and mitigate antibiotic resistance dissemination in composting systems, offering novel insights into the interactions among MPs, ARGs, and microbial communities.