Isolation And Characteristics Of 1,4-dioxane-degrading Strain And The Preparation Of Microorganism Agent

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.The induction process was not required in 1,4-dioxane degradation from this investigation.These characteristics not only solve the problems of amplification culture of environmental microbiology,but also ensure the stability of biodegradation used in wastewater treatment.On this basis,the cell specific growth rate has been greatly enhanced by optimizing medium,and then further application has been done to obtain a large number of cells by fermentation.Furthermore,the cells were prepared as the microbial agents,which could maintain well degradation activity and save for a long time as the product.In this study,the optimum pH and temperature for 1,4-dioxane degradation has been required by modifying environmental factors.This strain could grow well in the poor nutritional and has less effect on the level of the initial substrate concentration.This indicated that the strain has well competitive in the environment.The effect of medium composition of salinity,nitrogen sources and carbon source on the degradation activity has been investigated.It showed that the high salinity inhibit the growth of cells and the degradation of 1,4-dioxane,whereas the inorganic nitrogen sources has not significantly effect on the degradation activity.In addition,the organic nitrogen sources and second carbon sources could greatly improve the degradation activity.Furthermore,the intermediates of 1,4-dioxane-degrading have been detected by analysis of GC/MS and the possible degradation pathway has been conducted.1,4-Dioxene,ethylene glycol and oxalic acid has been found as intermediates of 1,4-dioxane-degrading in this research.And a newly monooxygenase of 1,4-dioxane-degrading enzymes may play a role in catalyzed oxidation.In a word,a more perfect degradation pathway has been reasoned out,which base on the intermediates and the nature of enzymes.Degradation characteristics of cyclic ethers by strain DT8 bas been researched by the interactions of a variety of substrate,which found that the degrading-enzymes of strain DT8 may exist different binding sites of 1,4-dioxane and THF,respectively.It is more interesting that the degradation rate of 1,4-dioxane can been promoted in the presence of THF,while the degradation rate of THF has been inhibited by the degree.All of these will lay sound foundation for the application of biological purification of waste water and off-gas containing 1,4-dioxane.