Xanthobacter flavus DT8降解二噁烷的特性研究

对上海某医药厂污水站好氧池的活性污泥进行长期驯化,分离到1株能以二噁烷为唯一碳源和能源生长的菌株DT8.经生理生化、脂肪酸鉴定和16S rRNA序列分析,确定该菌株为黄黄色杆菌DT8(Xanthobacter flavus DT8).序批实验表明X.flavus DT8可于48 h内完全降解100 mg.L-1二噁烷,并可实现污染物的矿化.随着生物量的增加,该降解过程的细胞得率(以二噁烷计)为0.62 g.g-1,能量消耗系数(δe)为1.00,表明X.flavus DT8代谢二噁烷消耗的能量较少.研究不同温度、pH和营养条件对二噁烷降解的影响,发现二噁烷降解较适宜的温度和初始pH分别为34℃和7.0;在贫营养条件下,即无机盐培养基稀释100倍时,100 mg.L-1二噁烷于48 h的降解率达到65.6%.对X.flavus DT8降解二噁烷可能的诱导机制进行初步研究,结果表明X.flavus DT8对二噁烷的降解不需要经历诱导的过程.本研究揭示了X.flavus DT8直接代谢二噁烷的特性,为生物法净化含二噁烷废水及废气的工程应用奠定了基础.

Characteristics of 1,4-Dioxane Degradation by Xanthobacter flavus DT8

A strain DT8 was isolated from the activated sludge using culture enrichment technique,and subsequently identified as Xanthobacter flavus based on the analysis of morphological and physiological characteristics as well as cellular fatty acid composition and 16S rRNA sequence.X.flavus DT8 could effectively utilize 1,4-dioxane as the sole carbon and energy source,and was able to completely degrade 100 mg·L-1 substrate within 48 h.The values of biomass yield and energy discrepancy index were 0.62 g·g-1 and 1.00,respectively,indicating that low energy share was dissipated.The optimum pH and temperature for 1,4-dioxane degradation were 7.0 and 34℃,respectively.The degradation could also be performed in poor nutrition solution,e.g.the degradation ratio reached 65.6% even though in a 100-fold diluted medium.The induction process was not required in 1,4-dioxane degradation from this investigation.The characteristics of 1,4-dioxane degradation by X.flavus DT8 in direct metabolic mode was therefore revealed in this paper,and it will built a solid foundation for the application of biological purification of waste water and off-gas containing 1,4-dioxane.