Xu Peng, Ma Wencheng, Han Hongjun, Hou Baolin, Jia Shengyong
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China E-mail:
Water Sci Technol. 2014;70(6):1129-34. doi: 10.2166/wst.2014.356.
A bacterial strain, QWE-5, which utilized naphthalene as its sole carbon and energy source, was isolated and identified as Streptomyces sp. It was a Gram-positive, spore-forming bacterium with a flagellum, with whole, smooth, convex and wet colonies. The optimal temperature and pH for QWE-5 were 35 °C and 7.0, respectively. The QWE-5 strain was capable of completely degrading naphthalene at a concentration as high as 100 mg/L. At initial naphthalene concentrations of 10, 20, 50, 80 and 100 mg/L, complete degradation was achieved within 32, 56, 96, 120 and 144 h, respectively. Kinetics of naphthalene degradation was described using the Andrews equation. The kinetic parameters were as follows: qmax (maximum specific degradation rate) = 1.56 h⁻¹, Ks (half-rate constant) = 60.34 mg/L, and KI (substrate-inhibition constant) = 81.76 mg/L. Metabolic intermediates were identified by gas chromatography and mass spectrometry, allowing a new degradation pathway for naphthalene to be proposed. In this pathway, monooxygenation of naphthalene yielded naphthalen-1-ol. Further degradation by Streptomyces sp. QWE-5 produced acetophenone, followed by adipic acid, which was produced as a combination of decarboxylation and hydroxylation processes.
分离出了一种以萘作为唯一碳源和能源的细菌菌株QWE-5，并鉴定为链霉菌属。它是革兰氏阳性、形成芽孢且有鞭毛的细菌，菌落完整、光滑、凸起且湿润。QWE-5的最适温度和pH分别为35℃和7.0。QWE-5菌株能够完全降解浓度高达100mg/L的萘。在萘初始浓度为10、20、50、80和100mg/L时，分别在32、56、96、120和144小时内实现了完全降解。使用安德鲁斯方程描述了萘降解的动力学。动力学参数如下：qmax（最大比降解速率）=1.56 h⁻¹，Ks（半速率常数）=60.34mg/L，以及KI（底物抑制常数）=81.76mg/L。通过气相色谱和质谱鉴定了代谢中间体，从而提出了一种新的萘降解途径。在该途径中，萘的单加氧作用产生萘-1-醇。链霉菌属QWE-5的进一步降解产生苯乙酮，随后产生己二酸，己二酸是通过脱羧和羟基化过程共同产生的。
