| Recently, the present of chlorothalonil production has up to8000t/a. It has the teratogenic, carcinogenic and cause mutation the rates kidney, according to a test to rat on high doses of chronic feeding. Some scholars who claimed that in high doses of animals has carcinogenicity of pesticide should be disabled because of chlorothalonil in high doses of animals have carcinogenicity. Also some scholars believed based on the discretion of the dose in the environment and ecological effect and decided to choose. Although of chlorothalonil belong to low toxicity Organochlorine pesticides, because of its physical and chemical properties stable, in the natural environment degradation slowly, has certain become widely distributed geographically and leaving farmland and agricultural pollution.This paper focuses on the research of chlorothalonil degradation bacterium screening, and identification, strains of chlorothalonil degradation characteristics of degrading enzymes, the degradation characteristics and enzymatic reaction dynamics, etc, for effective control of chlorothalonil for the wide use of farmland to pollution.From long-term application of of chlorothalonil soils, through the enrichment culture screen, crossed separating out high efficiency degradation bacterium B-7.According to the strains characteristics of biochemical and16S rDNA sequencing, it is belongs to the Pseudomanas.The bacteria can grow normally in20℃、25℃、30℃、35℃.It is growing slowly in the low temperature25℃and30℃, but can grow well in25℃and30℃, after training14d the degradation rate of the chlorothalonil reached in85.49%, in40℃the strain can not grow well. pH value on the influence of strain growth bigger, strains in the pH=6.0and pH=7.0would be growing, but in the pH=7.0grow well. In the pH=5.0, pH=8.0, pH=9.0against the growth of strains. The optimal conditions for the training is pH=7.0,30℃. Under the optimal conditions after training14d the degradation rate of the chlorothalonil reached in85.49%.According to the research of chlorothalonil degrading enzymes found in positioning B-7strains of the cytoplasm of enzyme secretion of chlorothalonil with the degradation of high effect, and in the medium of chlorothalonil conditions will secrete this enzyme, explain this enzyme belong to inducible enzyme. The enzyme degradation in20℃,25℃,30℃,35℃conditions are degradation of chlorothalonil, and40℃in when the enzyme activity is restrained, among them in30℃conditions reaction after4h degradation rate is the highest, about49.18%. PH enzymatic reaction to influence is bigger, pH=4.0, pH=5.0, pH=9.0by certain of the activity of an enzyme inhibition, and in pH=6.0, pH=7.0on the degradation of chlorothalonil rate is higher. The different metal ions have the different effect on the enzyme activity, Na+, K+, Ca2+, Mg2+do not have obvious effect on the enzyme activity, But the metal ion Mn2+and Fe3+,Cu2+, could reduce activity of the enzyme.According to the research of the effect of different amount of enzyme on the reaction rate and the effect of the different concentration of substrate on the reaction rate find out the process of the enzyme degrading chlorothalonil abide by the mie equation. With Lineweaver-Burk plot algorithm to find the Vmax and Km, namely to1/V on1/[S] mapping, draw a straight line, the straight line in the Y axis of intercept for1/Vmax, the X axis in the intercept for1/Km of absolute value. From the equation can calculate the Vmax=0.3896mg/L·min, Km=98.89mg/L... |
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