Determination of how tetracycline influences nitrogen removal performance, community structure, and functional genes of biofilm systems

Abstract

Abstract Antibiotic and antibiotic resistance genes (ARGs) have frequently detected in the effluent from wastewater treatment plants. Biological activated carbon (BAC) filter as a tertiary process was used to study the influence of tetracycline (TC) on nitrogen removal efficiency during exposure to tetracycline at different concentrations (0, 0.01, 0.1, 1, 5 mg/L) in an easily separated biofilm (interstitial organism) and inner biofilm (carbon-attached organism). High throughput sequencing and QPCR showed that exposure of 5 mg/L tetracycline increased the denitrifying genes (DNGs) and genera containing denitrification function (e.g., Acidovorax, Flavobacterium, unclassified_f_Comamonadaceae). Moreover, DNGs were mainly located in carbon-attached organisms, while the resistance genes were primarily found in interstitial organisms. The presence of TC stimulated the generation of resistance genes and DNGs, leading to enhanced nitrogen removal. Approximately 90% of the total resistance genes in interstitial organisms and 85% of the TC were effectively removed in the developed biofilm system. Overall, the results indicated that the biofilm system was a good choice for treatment of sewage treatment with a certain amount of TC and control over the contamination of resistance genes.