Isolation, identification, degradation characteristics and mechanisms of decabromodiphenyl ether degrading bacteria

Abstract:

[Background] Decabromodiphenyl ether (BDE-209) is one of the most widely used brominated flame retardants, which has caused serious harm to ecological environment and organisms due to its persistent toxicity. [Objective] To obtain an aerobic bacterium that could effectively degrade BDE-209 and to study its degradation characteristics and mechanisms. [Methods] The aerobic degrading bacterium was isolated from activated sludge by enrichment, isolation and purification using BDE-209 as the sole carbon source. The concentration of BDE-209 and the intermediate products were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS), respectively. [Results] A BDE-209 aerobic degrading strain F was screened and preliminarily identified as Pseudomonas nitroreducens. Under the optimal degradation conditions of 30℃, pH 7.0, 10% inoculum volume and 250 mg/L glucose, the degradation efficiency reached 76.2% for 10 mg/L (initial concentration) BDE-209. Obvious effects of low Cd²⁺concentrations (≤5 mg/L) on BDE-209 biodegradation and the growth of P. nitroreduc ens were not observed, while the effects of high Cd²⁺concentrations (≥15 mg/L) were significant. In addition, BDE-209 affected cell surface hydrophobicity to some degree. The biodegradation mechanisms of BDE-209 mainly included debromination, hydroxylation, cleavage of diphenyl ether bonds and ring opening. [Conclusion] Strain F showed good biodegradation ability for BDE-209. The research results facilitated the aerobic microbial degradation of BDE-209 and the bioremediation of BDE-209 polluted environment.

Key words:decabromodiphenyl ether;strain F;microbial degradation;cell surface hydrophobicity;degradation mechanism