Metagenomic Insights into the Microbial Community of Activated Sludge in Oxytetracycline Wastewater Treatment

The overuse of antibiotics in human society poses a global health challenge, necessitating effective treatment of antibiotic production wastewater. This study examines the microbial community within activated sludge in anaerobic digestion (AD) and biological nutrient removal (BNR) systems at a full-scale oxytetracycline production wastewater treatment plant. The AD system effectively degraded polysaccharides but accumulated refractory humic-like substances, as determined by excitation–emission matrix fluorescence spectroscopy. Metagenomic analysis revealed distinct microbial communities between the AD and BNR systems, with Bacteroides (13.9%) and Proteiniphilum (33.5%) as the most abundant genus in the AD and BNR systems, respectively. Functional gene analysis showed a high presence of carbohydrate binding and glycoside hydrolases. The low abundance of nitrite oxidizer and the nxr gene might explain nitrite accumulation in the BNR system via partial nitrification. The antibiotic resistance genes (ARGs) affiliated with tetracycline were dominant in both the AD and BNR systems, with 45% of tetracycline and 20% of total ARGs being efficiently removed during the anaerobic treatment. The findings of this study can provide insights into microbial response to oxytetracycline production wastewater, informing the optimization of biological treatment processes and mitigating the environmental impacts of antibiotic production.