Analysis of aerobic granules under the toxic effect of ampicillin in sequencing batch reactors: Performance and microbial community

Abstract

To study the change of the aerobic granules' microbial community in the present of antibiotics, ampicillin (AMP) was selected as a model component. With acetate as carbon source, different concentrations of AMP (5, 10 and 15 mg L−1) were applied to the inflow intermittently and the results showed that the stability of the aerobic granules was maintained below 10 mg L−1 AMP. Simultaneously, under exposure to 5 and 10 mg L−1 AMP, the COD removal efficiency in the batch reactors remained at 86% and AMP was degraded almost completely with a removal efficiency of 97%. However, the EPS concentration and dehydrogenase activity decreased constantly with increasing AMP dosage.High-throughput sequencing analysis revealed that Proteobacteria was the most prominent phylum in the whole experiment and contributed to the degradation of AMP. The percentages of Azoarcus and Mycoplana increased at 10 mg L−1 AMP. In addition, Hydrogenophaga and Enterococcus played a key role in the microbial metabolism.