Spatiotemporal dynamics of antibiotic resistance genes and bacterial communities in leaf biofilms of submerged macrophytes: Assessing wastewater treatment ecological pond

Abstract

Submerged macrophyte phyllosphere-associated biofilms serve as a critical reservoirs and potential transmission vectors for antibiotic resistance genes (ARGs), potentially exacerbating ecological risk in aquatic ecosystems. In this study, metagenomic sequencing and microbial community profilingwere employed to systematically investigate the spatiotemporal ARGs dynamics in Vallisneria natans phyllosphere-associated biofilms within an ecological purification pond. Key findings identified that multidrug resistance (MDR) genes constituted 39 % of the total detected ARGs in the phyllosphere-associated biofilms, exhibiting 11.3 % higher abundance compared to the aquatic biofilms (35 % of total detected ARGs). Principal coordinates analysis demonstrated significant segregation between the phyllosphere and adjacent water biofilm resistomes, explaining 48.76 % of the variance and indicating plant-mediated selection of resistant microorganisms via microenvironmental modification. Seasonal variation predominates over spatial in structuring microbiota and ARGs, with taxa-specific monthly shifts. Microbial community profiling identified Pseudomonas (50.8 %) and Bacteroidetes (11.35 %) as the dominant phyllosphere taxa, exhibiting significant correlations with key environmental parameters. Specifically, Pseudomonas abundance positively correlated with water temperature (R² = 0.51, P < 0.01), while Bacteroidetes showed a temperature-independent association with the oxidation-reduction potential (R² = 0.48, P < 0.05). Linear discriminant analysis effect size identified Diatoms (14.31 %) as a biomarker group, suggesting that photosynthesis-driven carbon exchange enhances algae-bacteria symbiosis. Finally, co-occurrence network analysis established Pseudomonas and Flavobacterium as the potential ARG hosts. These findings provide valuable insights for optimizing the design of ecological purification ponds and developing targeted ARG control protocols in aquatic ecosystems.