Revealing Dual Synergistic Strategies in Sulfate-Reducing Microbiomes for Sulfamethoxazole Biodegradation via DNA-SIP and Metagenomics.

Abstract

Sulfate-reducing microbiomes (SRMs) have shown strong potential for antibiotic remediation, yet the active microorganisms and community-level strategies associated with sulfamethoxazole (SMX) biotransformation remain poorly understood. In this study, long-term bioreactor operation (269 days; 500-1500 μg/L SMX), DNA-stable isotope probing (DNA-SIP), and metagenomic analyses were integrated to investigate the microbial contributors and functional organization underlying SRM-driven SMX biotransformation. Desulfobacterium, a key SRM member, was co-enriched with Geobacter and Leptolinea in the 13C-labeled heavy fraction, suggesting potential metabolic complementarity during community-level SMX biotransformation. Genome-resolved analyses further revealed structured patterns of inferred horizontal gene transfer (HGT) and predicted metabolite exchange among keystone taxa. The transferred genes were mainly associated with energy conservation, transport, sulfur-associated metabolism, and stress-response functions, whereas the predicted exchanged metabolites included carbon metabolites, amino acid-related sulfur compounds, purine-related intermediates, and cofactor-associated metabolites. Together, these findings suggest that HGT-associated functional redistribution and metabolic complementarity may contribute to the persistence and coordinated activity of sulfate-reducing microbiomes under high SMX stress. This study links SIP-identified active populations with genome-inferred interaction patterns in a sulfate-reducing system and provides new insight into microbiome-based anaerobic strategies for antibiotic-containing wastewater treatment.