Impacts of non-spherical polyethylene nanoplastics on microbial communities and antibiotic resistance genes in the rhizosphere of pea (Pisum sativum L.): An integrated metagenomic and metabolomic analysis

The ecological effects of nanoplastics (NPs) has become a growing concern; however, the influence of non-spherical NPs-which better represent real-world morphologies-remains poorly understood. This study investigated the impact of non-spherical polyethylene (PE) NPs on the growth of pea (Pisum sativum L.) and its rhizosphere microenvironment across different concentration levels (0, 20, and 200 mg/kg) using integrated metagenomics and metabolomics. Results showed that high-dose (200 mg/kg) exposure significantly inhibited plant growth. Although soil physicochemical properties remained unchanged, the rhizosphere microbial communities experienced significant restructuring, characterized by a marked enrichment of Pseudomonas and a reduction in beneficial Rhizobium populations. Metagenomic analysis revealed a concurrent increase in the abundance and diversity of antibiotic resistance genes (ARGs) under non-spherical PE-NP stress. This was accompanied by a shift in bacterial host composition, with a trend toward a higher prevalence of potentially pathogenic taxa such as Pseudomonas aeruginosa. Metabolomics analysis further revealed that non-spherical PE-NPs altered the rhizosphere metabolite profile, thereby significantly driving the succession of ARG hosts. Our integrated analysis enhances the understanding of how non-spherical PE-NPs disrupt microbial communities and elevate the risks of ARGs in rhizosphere soil, highlighting the significance of incorporating environmentally relevant NPs into environmental risk assessments.