Enhanced biodegradation of 2,4,6-tribromophenol by a novel dehalogenase purified from Bacillus sp. GZT

As a typical flame retardant, 2,4,6- tribromophenol TBP has a wide range of application and can be easily transmitted into the biota and environment, resulting various health hazard. Although many researches were mainly... [ view full abstract ]

As a typical flame retardant, 2,4,6- tribromophenol TBP has a wide range of application and can be easily transmitted into the biota and environment, resulting various health hazard. Although many researches were mainly focused on the debromination and mineralization of TBP by isolated bacteria, barely research has been attempted to specifically investigate the enhanced biodegradation of TBP by a newly enzyme. In this study, the purification process as well as their application properties of the dehalogenase isolated from Bacillus sp. were investigated. The results showed a novel TBP dehalogenase, capable of rapidly biodegrading TBP, was purified and characterized for the first time. Overall 46.7-fold purification of enzyme with recovery of 28.6% and final specific activity of 18.9 U/mg was obtained using progressively purification protocol. The molecular mass of this enzyme with an isoelectric point (pI) of 8.45 was estimated to 63.4 kDa by SDS-PAGE. Characterization of N-terminal amino acid sequence revealed this enzyme has high similarity with oligopeptide ABC transporter oligopeptide-binding protein and peptide ABC transporter substrate-binding protein. Up to 80% degradation efficiencies was achieved by TBP dehalogenase within 120 min under optimal conditions. Addition of H2O2, NADPH, Mn2+ and Mg2+ can greatly promote enzyme reaction, whereas the activities were strongly inhibited by EDTA, methyl viologen, Ni2+, Cu2+, Ca2+ and Fe2+. Measured Km value (73 µmol/min/mg) and Vmax (0.63µmol/L) for TBP degradation indicated this dehalogenase can specifically eliminate TBP with high efficiency and favorable stability. This pioneer report demonstrated this newly-isolated TBP dehalogenase is effectively involved in biodegradation of TBP.