Biocathode regulates enrofloxacin degradation by coupling with different co-metabolism conditions.

In this study, biocathode system coupled with different co-metabolism conditions (NaAc, glucose and NaHCO) were developed to degrade quinolones enrofloxacin (ENR) due to its poorly metabolization, easily accumulation and potential toxicity. Simultaneously, ENR reduction kinetic rate constant in NaAc-fed, glucose-fed and NaHCO-fed biocathodes, and sole biocathode were increased by 343.62%, 320.46%, 189.19% and 130.88% when compared with that of abiotic cathode when the operational time and ENR concentration were set to 48 h and 25 mg/L. In addition, transformation pathways of ENR revealed pathway II were dominantly occurred in NaAc- and glucose-fed biocathode while pathway IV acting as key metabolic process were shown in NaHCO-fed biocathode. Moreover, 16S rRNA high-throughput sequencing analysis indicated that biocathodic communities were sensitive to switch-over of carbon source, namely Delftia and Bosea as organohalide-respiring bacteria (OHRB) were abundant in NaAc- and glucose-fed biocathodes while Mesotoga and Syntrophorhabdus that responsible for benzoyl-CoA metabolic process were enriched in NaHCO-fed biocathode. Overall, this study could unravel the underlying relationship between biocathode degradation pattern of ENR and different co-metabolism conditions, and further offer valuable scientific information on treating refractory quinolones antibiotics via green bioelectrochemical method.