Mechanisms of Sulfamethoxazole biodegradation in mangrove rhizosphere by metagenomic and metabolic pathways

Sulfamethoxazole (SMX) is extensively employed as an antibiotic, posing significant challenges to both marine ecosystems and human health that cannot be disregarded. In this work, we investigated the performance of mangrove rhizosphere on SMX biodegradation along with the distance to rhizoplane by comprehensively exploring the change in physicochemical properties, SMX metabolites, enriched potential bacterial communities and SMX-degrading genes. Our results exhibited a significant decrease of pH value, and increase of sediment organic matter, low-molecular-weight organic acids and some enriched potential SMX degraders of Nocardioidaceae , Intrasporangiaceae , Geobacteraceae , Bacillaceae , Comamonadaceae , Micromonosporaceae , Burkholderiaceae and Xanthobacteraceae by mangrove rhizoplane, which achieved the best SMX removal efficiency (72.00 %) in the layer with 2–3 mm distance to mangrove rhizoplane. The abundance of SMX-degrading genes ( fadA , pcaF , catE , mhpD and mhpE ) were increased in mangrove rhizosphere, leading to the change in SMX metabolism, primarily the 4-aminobenzenesulfonic acid pathway. We suggest that the degradation of SMX within mangrove rhizosphere is primarily influenced by physicochemical properties, bacterial community composition and SMX degradation pathways in compartments close to rhizoplane. • Mangrove rhizosphere improved SMX degradation. • More microbes were involved in SMX degradation in mangrove rhizosphere. • SMX degradation-related genes were enriched in mangrove rhizosphere. • Mangrove rhizosphere promoted 4-aminobenzenesulfonic acid pathway.