Does the Coexistence of Common Antibiotic and Metal Fuel Resistance Genes and Reshape Bacterial Community in Polluted Rivers?

Surface water often receives effluent discharges from WWTPs, and agriculture runoffs reportedly contribute to sulfamethoxazole (SMX) and its resistance in river environment. SMX is commonly found antibiotics in the environment due to its overuse, causing persistent exposure to aquatic bacteria. SMX and Copper (Cu) can attribute to AMR emergence in the sensitive population, potentially inducing the community shift among the existing riverine bacteria. This study investigated the individual and combined effects of SMX and Cu on antibiotic resistance gene pattern and native populations in mesocosm reactors. Experiments were conducted with distinct conditions to monitor the water quality parameters, uidA, sul2, intI1, and bacterial diversity. The findings indicated that uidA declined significantly within 24 h in all reactors. Contrastingly, sul2 and intI1 did not decline drastically within 24 h, exhibiting a different trend, explaining their persistence up to 168 h. The 16S sequencing data across the reactors revealed the community shifts at genus level within 24 h, from predominance of Arcobacter (38%), Bacteroides (1.53%), and Cloacibacterium (1.12%) to Arcobacter (6%), Bacteroides (0.15%), and Cloacibacterium (0.22%). This study emphasizes that water quality parameters are significant determinants for the prevalence of ARGs in a highly contaminated riverine.