Simultaneous Cr(VI) removal and 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) biodegradation by Pseudomonas aeruginosa in liquid medium

Abstract

Simultaneous Cr(VI) removal and 2,2′,4,4′-tetra brominated diphenyl ether (BDE-47) biodegradation by Pseudomonas aeruginosa in liquid medium were investigated in this study, with the goal of elucidating the interaction between concomitant pollutants Cr(VI) and BDE-47 during microbial remediation. The experimental results revealed that the degradation efficiency of 1 mg L−1 BDE-47 by 60 mg L−1 biomass achieved 51.3% within 7 d when 2 mg L−1 Cr(VI) coexisted. The degradation efficiency was accelerated at low concentrations of Cr(VI) (≤5 mg L−1), but inhibited at higher levels (≥10 mg L−1). Cr(VI) of 2 mg L−1 facilitated the secretion of rhamnolipid from the strain, altered cell surface hydrophobicity and cell membrane permeability, and promoted intracellular BDE-47 accumulation, thus improving BDE-47 biotransformation. In addition, the stimulation of intracellular enzyme synthesis by 2 mg L−1 Cr(VI) contributed to more BDE-47 elimination in the cells. The achievement of BDE-47 biodegradation was coupled with cell growth, enzyme extraction, cell membrane permeability change, and ATPase activity increase. The study also indicated that the improvement of Cr(VI) removal in BDE-47/Cr(VI) co-contaminated condition was mostly due to the increasing synthesis of extracellular enzyme in the presence of low concentrations of BDE-47. The whole study demonstrated that P. aeruginosa was available for the removal of toxic Cr(VI) and degradation of BDE-47 simultaneously in the liquid.