From Interface to Cell: The Complex Interaction and Transfer Process Coupling Mechanism between Microplastics and Antibiotic Resistance Genes

Microplastic-phase interfaces (MPPIs) were established as critical vectors for accelerating antibiotic resistance gene (ARG) dissemination. Through integrated anaerobic/aerobic wastewater treatment system experiments combined with physicochemical characterization, metagenomic sequencing, and molecular dynamics simulations (MD), we elucidated MP-ARG interaction mechanisms from the interfacial to the cellular scale. Polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) MPPIs underwent significant aging during 60 days of exposure, resulting in elemental enrichment (C/O/P), the formation of C═C/C-H/C-O/C-OH functional groups, and elevated oxidation. These transformations enhanced extracellular polymeric substance production (184.81 mg/g MLSS) and selectively enriched antibiotic-resistant bacteria, ARGs, and mobile genetic elements (MGEs), promoting horizontal gene transfer. XDLVO theory revealed spontaneous microbial adhesion (Δ<i>G</i>_adh = -23.63 mJ/m²) driven by Lifshitz-van der Waals (LW) and acid-base interactions. MD demonstrated direct MP penetration into the membrane via dominant LW forces (-1200 kJ/mol) and increased permeability. Concurrently, compared with sewage water (SW), MPPIs induced a 2.06-fold overproduction of reactive oxygen species, which upregulated genes encoding efflux pumps (<i>acrF</i>, 3.2-fold), outer membrane porins (<i>OmpF</i>, 4.1-fold), and conjugative transfer genes (<i>traF,</i> 3.8-fold). Material-specific (PET > PE > PP) and oxygen-driven redox mechanisms governed ARG dissemination: aerobic conditions favored radical-driven oxidation and MGE entrapment, whereas anaerobic systems enhanced hydrophobic adhesion.