Removal of dibutyl phthalate (DBP) by bacterial extracellular polymeric substances (EPS) via enzyme catalysis and electron transmission

Phthalic acid esters (PAEs) showed high environmental risk due to the widely existence and toxicity. Microbial-excreted extracellular polymeric substances (EPS) showed potential of degrading organic compounds. In this study, the degradation ability and the mechanisms of EPS from two bacteria (PAEs degrader Gordonia sihwensis; electrochemically active strain Shewanella oneidensis MR-1) were investigated. Results showed that EPS of the two bacteria had different composition of C-type cytochromes, flavins, catalase, and α-glucosidase. The removal of dibutyl phthalate (DBP) by total EPS were 68% of G. sihwensis and 72% for S. oneidensis. For both bacteria, the degradation rates k of EPS were as TB-EPS > LB-EPS > S-EPS. The degradation mechanisms of EPS from the two bacteria showed difference with electrochemical active components mediated electron transmission for S. oneidensis MR-1 and enzymes catalysis for G. sihwensis. Results of this study illustrated the variation of the contribution of active components of EPS to degradation. [Display omitted] •The EPS of S. oneidensis MR-1 and G. sihwensis showed different composition.•For both bacteria, the degradation performances of EPS: TB-EPS > LB-EPS > S-EPS.•EPS of S. oneidensis MR-1 degraded DBP mainly via EET with higher c-Cyts and flavins.•EPS of G. sihwensis mainly degraded DBP by enzyme (CAT and α-GC) catalysis.