Microbial community structure and nitrogen removal responses of an aerobic denitrification biofilm system exposed to tetracycline

We investigated the compositional shift of the microbial community and the denitrification performance of an aerobic denitrification system after exposure to tetracycline (TC), an antibiotic widely used to treat aquaculture organisms showing clinical signs of disease. TC substantially affected the microbial denitrifying community and its diversity. Microbial community richness reached maximum values at 50 mu g/L, however with minimum diversity. Proteobacteria was the dominant phylum and was enriched with increasing TC concentration. Marinobacter and Halomonas were the dominant genera in the reactor without TC, but Winogradskyella, Muricauda and Simplicispira were relatively abundant at higher antibiotic concentrations. Nitrate-N removal rates appeared substantially unchanged at 2 mu g/L TC, but significantly decreased (p < .05) at 5 and 20 mu g/L, and recovery of nitrate removal effectiveness was observed at 50 mu g/L TC.