Attenuation of sulfamethoxazole and associated antimicrobial resistome by enriched electroactive microbial consortia

Electroactive biofilms with the capacity of extracellular electron transfer (EET) have shown great promise for mitigating antibiotics and antibiotic resistance genes (ARGs). However, detailed interactions between antibiotics and electroactive microorganisms, along with ARGs dissemination dynamics within the electroactive consortia, remained poorly understood. In this study, stable electroactive microbial consortia were enriched, and their influences on the fates of sulfamethoxazole (SMX) and associated ARGs were systematically investigated. The results showed the enriched consortia could degrade SMX effectively within a wide concentration range through co-metabolism which was stimulated by their electrogenic respiration. Moreover, with accelerated SMX removal, the abundances of associated ARGs including sul1 and sul2 in the consortia decreased significantly due to alleviated SMX-induced selective pressure and probably weakened horizontal gene transfer mediated by mobile genetic elements (e.g., IS91 and tnpA). Degrader isolation and metagenomic analysis identified the core EET-proficient genera (e.g., Geobacter and Alcaligenes) as essential for the accelerated co-metabolism biodegradation of SMX, whereas the proliferation of other bacteria with limited or no EET capacity (e.g., Hydrogenophaga, Burkholderia, Comamonas, Desulfovibrio and Pseudomonas) was closely linked to the ARGs dissemination. This work provides a mechanistic elucidation of how electroactive microbial consortia stimulate antibiotic degradation and attenuate ARGs proliferation, offering strategic insights for risk control of the resistome during wastewater treatment.