Phytoremediation of antibiotics and antibiotic resistance genes (ARGs) by submerged macrophytes: Synergistic removal and mechanistic insights

Antibiotic resistance genes (ARGs) pose a major threat to human disease control and have emerged as a critical global public health concern. While aquatic plants are widely recognized for removing antibiotics, their efficacy in co-removing ARGs and underlying mechanisms remain poorly understood. To fill this gap, we systematically evaluated the removal effects and mechanisms of enrofloxacin (ENR), tetracycline (TC), sulfamethoxazole (SMX) and associated ARGs and mobile genetic elements (MGEs) by Hydrilla verticillata , a widespread aquatic macrophyte. Compared with controls without plant, H. verticillata significantly enhanced TC, ENR, and SMX removal efficiencies by 7.8 %, 38.1 %, and 8.5 %, respectively. Concurrently, it reduced the abundance of ARGs and MGEs by 7.21–86.8 %, confirming its novel dual co-removal function. Notably, plant uptake contributed only 0.03–6.3 % to antibiotic removal. Instead, removal relied on H. verticillata -mediated microbial regulation: mitigating antibiotic-induced microbial detriment, maintaining diversity, and enriching degrading bacteria. We further found that aquatic plants alleviated the risk of ARG dissemination by enhancing microbial diversity, narrowing the potential host range, and simplifying ARG transmission networks. Critically, partial least squares path modeling revealed that MGEs were the primary drivers of ARGs dynamics in treatments with plant (path coefficient: 0.840), whereas antibiotic selection pressure dominated without plant (path coefficient: 0.875). These findings highlight the dual role of H. verticillata in antibiotic removal and ARG suppression, providing novel insights into phytoremediation as a sustainable strategy for restoring antibiotic-contaminated aquatic environments and combating antimicrobial resistance.