Biodegradable microplastics amplify antibiotic resistance in aquaculture: A potential One Health crisis from...

Aquaculture has become a reservoir for antibiotic resistance genes (ARGs) and microplastics (MPs), threatening food security and human health. However, the role of MPs, in ARGs dissemination remains unclear. Here, we tracked ARGs dynamics in tilapia aquaculture systems via a 90-day in situ MPs-exposure experiment, and compared the impacts of conventional polypropylene MPs (PP-MPs) and biodegradable poly (butylene adipate-co-terephthalate) MPs (PBAT-MPs) on resistome distribution, ecological risks, and microbial assembly across water, sediment, plastisphere, and fish guts via metagenomics. Results revealed the MPs served as microbial scaffolds, enriching microbiome and resistome. Species turnover (>80 %) and deterministic process induced by MPs dominated the microbial community assembly. Astonishingly, PBAT-MPs posed higher risks compared to PP-MPs based on risks ranking (Rank I ARGs and risk index) and pathogen identification (37 % and 34 % of clinical ARGs, respectively). Stronger correlations were built in plastisphere between the microbial communities and ARGs (r > 0.8 and p < 0.05). Microbes (path coefficient = 0.632, p < 0.01) and MGEs (path coefficient = 0.344, p < 0.01) jointly exerted positive correlations with the ARGs profile. With sediments and MPs functioning ARGs reservoir and vectors, resistome dissemination mediated by plastisphere biofilm evolution were potentially exacerbated through trophic accumulation. By integrating multi-compartment resistome mapping (sediment reservoir-MPs vector-fish exposure), we established MPs as amplifiers of ARGs across trophic chains, directly linking environmental dynamics to human dietary exposure risks, thereby advancing environmental sustainability, food safety and antimicrobial resistance governance under One Health Perspective.