Co-metabolism of 4-bromophenol by Pseudomonas sp. EN-4 and toxicity evaluation of biotransformed samples

Abstract

Bromophenols, the building blocks of polybrominated flame retardants (PBFRs) constitute an important class of pollutants as they had been reported from different types of ecosystems across the earth. The improper disposal of PBFRs containing electronic waste (e-waste) and wastes from industrial units is of concern due to their recalcitrant nature and acute toxicity. In the current study Pseudomonas sp. EN-4 was able to metabolise 4-bromophenol (4-BP), a model representative of bromophenols in presence of phenol as a co-substrate. The isolate withstand the extreme pH (5.0–10.0) and salinity conditions (0.5–2% w/v) and maintain its degradation potential in presence of different metal ions prevalent at contaminated sites. The HPLC and MS analysis of biotransformed samples revealed the formation of catechol, which might get channelized to the central metabolic pathway by catechol 1,2-dioxygenase mediated ortho-cleavage of the aromatic ring. Further, > 70 % transformation of 2-bromophenol (20 mg/L), 2,4,6-tribromophenol (20 mg/L) and 3,3’,5,5′-tetrabromobisphenol A (10 mg/L) indicates the metabolic versatility of strain EN-4. A significantly lower toxic potential of biologically treated samples on Vigna radiata and Channa punctatus validated the utility and efficacy of EN-4 cells. These findings lay the foundation for future studies in developing a site specific treatment system for bioremediation of waste generated by e-waste processing and other similar units.