Effect Of Tomato Root Exudates On The Growth And Degradation Capacity Of Chlorpyrifos-degradating Strain Cupriavidus Nantongensis X1 Labled By LuxAB

In order to explore the role of tomato root exudates in the biodegradation of chlorpyrifos,different concentrations of tomato root exudates and their 8 major specific components(xylose,fructose,glutamic acid,leucine,aspartic acid,citric acid,malic acid and succinic acid)were collected and analyzed their effect on the growth and degradation of chlorpyrifos and its degradation product TCP.The results are as follows:1.Tomato root exudates were collected,dehydrated and diluted into different multiples(1x,5x,10x and 20x)with inorganic salt medium,which were used as the culture medium of the degrading bacteria Lux-Xl,the faster growth rate and the more colonies were observed as the concentration increased.2.Chlorpyrifos was degraded by Lux-X1 with the initial concentration of 20 mg·L-1,different multiples of tomato root exudates solution as the degradation system.Results showed that there was a significant promotion in the addition of tomato root exudates,and the optimal degradation was under 10 times of root exudates.3.8 root exudates components(xylose,fructose,glutamic acid,leucine,aspartic acid,citric acid,malic acid and succinic acid)were added into the inorganic salt medium to a final concentration of 100 mg·L-l,the effects of each component on the growth of Lux-X1 bacteria were observed,and it was found that all 8 components could promote the growth as carbon source,the promotion effect turned to be that glutamic acid=aspartic acid>leucine>malic acid>succinic acid>citric acid=xylose>fructose,the overall effect turned to be that the amino acids>organic acids>saccharides.4.The degradation effects of chlorpyrifos by Lux-X1 strain under 8 root exudates were as follows:the saccharides inhibited the degradation of chlorpyrifos while the amino acids promoted the degradation,and there were no obvious effect of organic acids.All components accelerated TCP degradation except saccharides,and amino acids seemed to be more favorable than the organic acids.5.The degradation experiments were conducted with the combined root exudates components,and it was found that specific combination could produce a synergistic effect,the xylose in combination with other root exudates accelerated the degradation of chlorpyrifos,while the succinic acid was the opposite.The amino acids combination showed a positive effect on the degradation of TCP.