Minimum Effective Concentration of Streptomycin in Inducing Antibiotic Resistance

It has been demonstrated that antibioticresistancecould be selected for and enrichedunder high antibiotic concentrations in biological wastewater treatment systems. However, limit knowledge is known about the antibiotic concentrations in influents that exert selection for antibiotic resistance in biological wastewater treatment systems.Herein, this study investigated the long-term effects of different streptomycin concentrations on selection of antibiotic resistance in an aerobic biofilm reactor treating simulated antibiotic production wastewater(606 days)by using multiple culture-independent andculture-dependent methods. qPCR, high-throughput quantitative PCR and metagenomic sequencing were used to detected ARGs and MGEs.Although the efficient COD removal from 88.52% to 92.83%was observed across all six stages (streptomycin: 0, 0.1, 1, 5, 25, 50 mg/L), increasing streptomycin concentration caused proliferation of ARB, ARGs and MGEs.And the Minimum effectiveconcentration of streptomycin causing a significant increase of relative abundance of ARGs and MGEs was at the levels ranging from 1 to 5 mg•L-1. This work proposed an experimental significant effect concentration which can guide implementation of antibiotic emission limits into biological treatment systems.