Peri-URban ecosystems (PURE) promote faster antibiotic and ARG degradation: Insights from a microcosm experiment

Urbanization has caused an increase in the contamination of aquatic environments, particularly with antibiotics and antibiotic resistance genes (ARGs), which present significant risks to both ecological and public health. This study aimed to evaluate the degradation of antibiotics and ARGs in urban and peri-urban environments (PURE) using a microcosm experiment with water and sediment samples collected from both areas. The degradation process was enhanced through two treatments: photocatalysis and immobilized laccase enzymes. The results revealed that PURE environments, particularly when combined with photocatalytic treatments, significantly outperformed urban environments in terms of both antibiotic and ARG degradation. Specifically, the combination of PURE water with photocatalysts achieved the highest clearance rates for antibiotics and the most significant reduction in ARGs. Additionally, structural equation modeling (SEM) revealed that microbial richness and environmental factors, such as pH and EC, were key drivers in both antibiotic and ARG removals. Further, degradation pathways of antibiotics like norfloxacin and tetracycline were examined, showing how different treatments facilitated breakdown at the molecular level, with PURE water treatments resulting in the most extensive molecular transformations. Ecological risk assessments indicated that PURE treatments, especially with immobilized laccase, posed the lowest environmental risk. This study highlights the potential of PURE ecosystems, especially with catalytic treatments, can effectively mitigate antibiotic resistance and improve urban water quality.