Department of Microbiology, Bose Institute, P-1/12, C.I.T. Scheme VII M, Kolkata, India.
Department of Microbiology, Bose Institute, P-1/12, C.I.T. Scheme VII M, Kolkata, India.
Chemosphere. 2013 Mar;90(10):2571-7. doi: 10.1016/j.chemosphere.2012.10.101. Epub 2012 Dec 1.
The present study describes the assimilation of di-n-octyl phthalate by an aerobic bacterium, isolated from municipal waste-contaminated soil sample utilizing di-n-octyl phthalate as the sole source of carbon and energy. The isolate was identified as Gordonia sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic and spectrometric analyses revealed a complete di-n-octyl assimilation pathway. In the degradation process, mono-n-octyl phthalate, phthalic acid, protocatechuic acid and 1-octanol were identified as the degradation products of di-n-octyl phthalate. Furthermore, phthalic acid was metabolized via protocatechuic acid involving protocatechuate 3,4-dioxygenase while 1-octanol was metabolized by NAD(+)-dependent dehydrogenases to 1-octanoic acid, which was subsequently degraded via β-oxidation, ultimately, leading to tricarboxylic acid cycle intermediates. Apart from phthalic acid and 1-octanol metabolizing pathway enzymes, two esterases, di-n-octyl phthalate hydrolase and mono-n-octyl phthalate hydrolase involved in di-n-octyl phthalate degradation were found to be inducible in nature. This is the first report on the metabolic pathway involved in the complete degradation of di-n-octyl phthalate by a single bacterial isolate, which is also capable of efficiently degrading other phthalate esters of environmental concern having either shorter or longer alkyl chains.
本研究描述了一种好氧细菌对邻苯二甲酸二辛酯的同化作用，该细菌从受城市垃圾污染的土壤样本中分离出来，利用邻苯二甲酸二辛酯作为唯一的碳源和能源。根据形态学、营养和生化特征以及 16S rRNA 基因序列分析，该分离株被鉴定为 Gordonia sp.。色谱和光谱分析的组合揭示了一个完整的邻苯二甲酸二辛酯同化途径。在降解过程中，鉴定出邻苯二甲酸单辛酯、邻苯二甲酸、原儿茶酸和 1-辛醇是邻苯二甲酸二辛酯的降解产物。此外，邻苯二甲酸通过原儿茶酸代谢，涉及原儿茶酸 3,4-双加氧酶，而 1-辛醇则通过 NAD(+)-依赖性脱氢酶代谢为 1-辛酸，随后通过β-氧化代谢，最终导致三羧酸循环中间体。除了邻苯二甲酸和 1-辛醇代谢途径酶外，还发现两种酯酶，邻苯二甲酸二辛酯水解酶和邻苯二甲酸单辛酯水解酶，参与邻苯二甲酸二辛酯的降解，它们具有诱导性质。这是第一个报道单一细菌分离株完全降解邻苯二甲酸二辛酯的代谢途径的报告，该分离株还能够有效地降解其他具有较短或较长烷基链的环境关注的邻苯二甲酸酯。
