Developmental dynamics of antibiotic resistome in aerobic biofilm microbiota treating wastewater under stepwise increasing tigecycline concentrations

This study aimed to investigate the impact of tigecycline, the third generation tetracycline, on the antibiotic resistance development in environmental microbiota. Two biological contact oxidation reactors containing aerobic biofilm microbiota were constructed, one of which was constantly fed with synthetic wastewater spiked with increasing concentrations of tigecycline (0 to 25 mg/L) under a hydrolytic retention time of 24 h. Over a period of 636 days, chemical oxygen demand removal over 90% and complete nitrification were achieved for both the control and tigecycline-exposed reactors, and effluent tigecycline concentrations in the tigecycline-exposed system were always