Root exudates drive metabolic remodeling of microbial and resistance to facilitate sulfonamide biodegradation in karst soil-carbonate rock interface.

Sulfonamide antibiotics have become pervasive contaminants in karst systems, where low carbon and rapid infiltration hinder natural attenuation, leading to persistent groundwater pollution and elevated antibiotic resistance risks. Although root exudates shape soil microbial metabolism and resistance, their role at the karst soil-carbonate rock interface remains unclear. This study demonstrates that artificial root exudates (ARE) significantly boost sulfamethazine (SMZ) removal at the soil-carbonate rock interface, achieving up to 92.0 % (35.1 % higher than control). Analyses of 16S rRNA gene sequences and metagenomes reveal that ARE remodels microbial communities by enriching potential degraders and upregulating genes for carbohydrate metabolism and xenobiotic degradation. Co-occurrence networks become more modular and recruit rare taxa as connectors, enhancing resilience through cross-module connectivity. ARE also reduces antibiotic resistance risks by suppressing sul1/sul2 hosts and key integrases. Nine metabolites were identified based on RRLC-MS/MS analysis, and four transformation pathways were proposed, confirming active biodegradation. Scanning electron microscopy further shows that ARE induces mineral dissolution and organic aggregation, creating porous microhabitats that facilitate SMZ degradation. This study offers novel insights into the coupled biotic-abiotic mechanisms of root exudates-mediated sulfonamide degradation at the low-carbon karst interface and provides a framework for plant-assisted antibiotic remediation in karst systems.