十溴联苯醚降解菌的分离鉴定、降解特性及降解机理

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

摘要:

【背景】十溴联苯醚(decabromodiphenyl ether，BDE-209)是应用最广泛的溴代阻燃剂之一，其持久性毒性给生态环境和生物体带来了严重危害。【目的】分离出一株能有效降解BDE-209的好氧细菌并研究其降解特性及机理，以探究BDE-209的微生物降解规律。【方法】以BDE-209为唯一碳源，通过富集、分离和纯化，从活性污泥中筛选出BDE-209好氧降解细菌。采用高效液相色谱(high-performance liquid chromatography,HPLC)和液相色谱-质谱联用仪(liquid chromatography-mass spectrometry，LC-MS)分别检测BDE-209的浓度和中间产物。【结果】筛选得到一株BDE-209好氧降解细菌F，经鉴定初步判定为硝基还原假单胞菌(Pseudomonas nitroreducens)。在30℃、pH7.0、接种量为10%(体积分数)、葡萄糖浓度为250mg/L的优化降解条件下，对初始浓度为10mg/L的BDE-209的降解率可达76.2%。低浓度的Cd²⁺(≤5mg/L)未对BDE-209的微生物降解和菌体生长产生显著影响，而高浓度的Cd²⁺(≥15mg/L)对BDE-209的微生物降解和菌体生长则产生显著影响。BDE-209对细胞表面疏水性(cell surface hydrophobicity，CSH)具有一定的影响。BDE-209的微生物降解机理主要包括脱溴、羟基化、二苯醚键断裂和开环等过程。【结论】菌株F对BDE-209具有很好的降解能力，研究结果对BDE-209的好氧微生物降解及BDE-209污染环境的生物修复具有较好的科学意义。

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.