Metagenomic Insights into Microplastic Micro-interfaces: Transforming Pollutants and Spreading Resistance.

Abstract

Microplastic micro-interfaces (MPMI) in wastewater treatment plants (WWTPs) serve as critical hubs for microbial colonization, pollutant transformation, and antibiotic resistance gene (ARG) dissemination. In this study, a large-scale genome-resolved metagenomic approach was employed to reconstruct 463 high-quality metagenome-assembled genomes (MAGs) from biofilms established on polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) within a municipal WWTP. Taxonomic profiling revealed that MPMI selectively enriched strict anaerobes and uncultured taxa, driving a profound ecological shift from the surrounding water and indicating the formation of localized hypoxic micro-niches. Functionally, the MPMI microbiome constructed a highly integrated metabolic network. Key dominant lineages were found to synergistically couple aromatic hydrocarbon degradation (via the shikimate pathway and β-oxidation) with complex carbon, nitrogen, and sulfur cycling, while deploying energy-efficient nucleotide salvage strategies to ensure biofilm stabilization under nutrient stress. Crucially, horizontal gene transfer (HGT) emerged as a fundamental mechanism for functional diversification, facilitating the active cross-genomic exchange of key adaptive traits associated with pollutant metabolism and biofilm regulation. Furthermore, MPMI harbored a highly diverse resistome comprising 36 ARG categories and 289 subtypes, highlighted by the critical genomic co-localization of mobile elements and clinical resistance markers (e.g., mcr-5.1, mupA) in core colonizers. Ultimately, these genomic insights elucidate the MPMI as a profound ecological hotspot driving the concurrent adaptation of metabolic networks and the resistome, thereby exacerbating the risks of ARG dissemination in aquatic environments.