邻苯二甲酸二（2?乙基己基）酯（DEHP）是一种高分子量的邻苯二甲酸酯（PAE），因高用量、难降解性成为一种全球性的有机污染物．从二沉池活性污泥中筛选出一株革兰氏阴性菌，能够以DEHP作为唯一碳源和能源，高效降解 DEHP，命名为 XB．基于其形态、生化特性以及16S rRNA 基因序列分析，鉴定为Pseudomonas sp．．优化其降解100 mg·L－1 DEHP的条件，结果表明最佳降解条件为：温度30—35℃，pH 7．0．同时，不同初始浓度下DEHP的降解动力学研究表明Pseudomonas sp． XB对DEHP的降解符合一阶动力学模型．当DEHP浓度为100 mg·L－1时，降解半衰期大约为8．25 h．通过GC?MS检测到了菌株XB降解DEHP的代谢产物，如邻苯二甲酸（2?乙基己基）单酯（ MEHP ）和2?乙基己基醇，推导了其降解途径．菌株Pseudomonas sp． XB还可以以其他3种常见PAEs（DMP、DEP、DBP）、苯酚、苯甲酸钠以及邻苯二甲酸等有机化合物为唯一碳源和能源生长，表明其降解环境有毒物质的能力．结果证明Pseudomonas sp． XB作为生态修复PAEs生物强化菌具有潜在的适用性．
Di?(2?ethylhexyl) phthalate (DEHP) is a high?molecular?weight phthalate ester (PAE) that has been considered as a global environmental organic pollutant due to its wide use and persistence characteristic. In this study, a novel gram negative bacterial strain, named XB, capable of utilizing DEHP as the sole source of carbon and energy was isolated from activated sludge taken from a municipal wastewater treatment plant through screening test. According to the analysis of morphology, physiological properties and 16S rRNA gene sequence, strain XB was identified as Pseudomonas sp.. Effects of environmental factors e.g. temperature, initial pH on DEHP degradation were optimized. Optimal temperature and pH value for DEHP degradation ( initial concentration was 100 mg·L-1) were determined as:30—35 ℃, pH 7.0. The degradation processes of DEHP under various initial DEHP concentrations by Pseudomonas sp. XB followed the first?order reaction model. The half-life of degradation was about 8. 25 h when the concentration of DEHP was 100 mg·L-1 . Mono?( 2?ethylhexyl) phthalate and 2?ethyl hexanol were determined as the intermediates by GC?MS analysis, and the degradation pathway was deduced. PAEs ( DMP, DEP, DBP ), and phenol, sodium benzoate, phthalic acid could also be utilized as the sole carbon and energy source for the cell growth. The results indicate that the bacterium may represent a promising application for DEHP bioremediation.
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