Biodegradation of chlortetracycline by acclimated microbiota

The wide presence of antibiotic chlortetracycline in the environment has aroused increasing ecological and human health concerns. Biodegradation can be a promising strategy to dissipate chlortetracycline. However, there is a paucity of knowledge on the biodegradation of chlortetracycline. The present study investigated the biodegradation of chlortetracycline by a microbial community in liquid culture, the potential intermediates, the influences of temperature, external carbon and nitrogen sources, and the composition of chlortetracycline-degrading microbial community. At the initial chlortetracycline level of 100 μg l−1, the average removal rates of 48.7% and 84.9% were achieved by acclimated microbial populations in one and four weeks, respectively. Four potential intermediates were identified using LC/MS/MS analysis. Moreover, microbial growth was observed with chlortetracycline biodegradation. Chlortetracycline could be used as sole carbon and nitrogen sources by the microbial community, while temperature rise and addition of external nitrogen source favored chlortetracycline biodegradation. Illumina MiSeq high-throughput sequencing analysis indicated that bacterial community structure considerably changed with the degradation of chlortetracycline. Firmicutes, Proteobacteria and Bacteroidetes were the dominant phylum groups in chlortetracycline-degrading bacterial community.