胁迫条件下DEHP降解菌的分离及特性研究

DEHP Degradation Bacteria under Stress Condition:Isolation and Characterization

为了获得邻苯二甲酸酯高效降解菌,该文用富集驯化的方法以复杂长链邻苯二甲酸二(2-乙基己基)酯(DEHP)为唯一碳源,从土壤中筛选出一株高效降解菌E1。经形态观察、生理鉴定、16S rDNA序列分析对菌株进行了分类鉴定,并对重金属离子、2-羟基吡啶,丙草胺胁迫条件下菌株的降解特性进行了分析,用GC-MS的方法测定中间代谢产物推测菌株降解途径。结果表明,菌株E1鉴定为紫色杆菌属Janthinobacterium sp.;最适降解条件为温度30℃、p H 7、盐浓度2%,6 d内对DEHP的降解率可达到96.8%~99.5%;浓度在300~1 200 mg/L范围内,降解符合一级反应动力学模型,t;在40~60 h之间;耐受100 mg/L的重金属离子Zn^(2+)、Pb^(2+)、Cd^(2+)、2-羟基吡啶,而对Cu^(2+)、丙草胺敏感;初步推测降解途径为:DEHP→DBP→MMP→PA,最终完全矿化为CO_(2)和H_(2)O。菌株E1不仅具有完全降解长链DEHP的能力,还有解决复杂环境中PAEs污染的潜力。

For the purpose of obtaining high effective phthalate ester degradation bacteria,the enrichment and domestication approaches were adopted involving the use of complex long-chain di-2-ethylhexyl phthalate (DEHP) as the sole carbon source,thereby a high efficiency degrading bacteria strain E1 was screened from the soil.Then the bacteria strain was classified and identified by means of morphological observation,physiological identification and 16S rDNA sequence analysis.Meantime,degradation characteristics of the strain under stress of heavy metal ions,2-hydroxypyridine and propanolamine were analyzed,and the degradation pathway of the strain was determined by GC-MS method.As a result,strain E1 was identified as Janthinobacterium sp;the optimal degradation condition were 30℃,pH 7 and 2% of the salt concentration;DEHP degradation rate could reach the range from 96.8%to 99.5%within six days,and the degradation fit the first-order reaction kinetics model when the concentrations of DEHP were within the range of 300~1 200 mg/L,and t;being within the range of 40 to 60 h.It was proved that the strain had strong tolerance to heavy metal ions (Zn^(2+),Pb^(2+) and Cd^(2+)) of up to the concentration of 100 mg/L,and to 2-hydroxypyridine of 100 mg/L;however,it was sensitive to Cu^(2+) and propanolamine.According to the tentative study,the DEHP degradation pathway followed the step:DEHP→DBP→MMP→PA,and eventually,DEHP was completely mineralized to CO_(2) and H_(2)O.In conclusion,strain E1possessed not only the capability to completely degrade long-chain DEHP,but also the potentials to tackle the PAEs pollution under complicated condition.