| Malathion as a low toxicity, good killing effect Organic phosphorus pesticide, is widely used in agricultural disaster prevention and grain storage. Extensive use lead to negative effect of soil and water pollution. Some studies have shown that many region’s water and soil polluted by malathion. To solve the serious environmental problem rapidly.Microbial remediation of organic phosphorus in soil, use metabolic activity of microbial to degrade pesticide residue in water is a safe, efficient, environmental protection measures. Separation and application of malathion degradation bacteria has become a hot research topic. The research of microbial degradation of malathion have made certain achievements at home and abroad, but the research of malathion degradation always in the laboratory, be limited in theoretical field, and commonly used in pure culture experiment. There are few research to study microorganism in natural water and soil, especially in soil environment. Research on application of degrading bacteria must solve the detection problem in soil and water. LuxAB gene marker technology provides an effective testing method for the study of degradation bacteria survival in soil and water. The Brevundimonas diminuta L19strains breserveed in our laboratory which is screened from soil with a high capability of degrade malathion. In order to process and its mechanism of further research and the strain in the soil colonization and degradation of malathion. In this study, plasmid pTR102that contained luxAB genes was successfully introduced into malathion-degrading strain Brevundimonas diminuta L19by electroporation.studied the ecological behavior of L19-luxAB stain and the degradation of malathion by stain L19in soil. The main results are as follows:1. studied the degradation of strain L19to different organophosphorus pesticides. The results show that strain L19has a wide degradation map to organophosphorus pesticides. The strain L19has different degradation ability to malathion, methyl parathion, parathion, methamidophos, chlorpyrifos, profenofos. When the initial concentrations were60mg/L,60mg/L,40mg/L,30mg/L,30mg/L,30mg/L,48h, degradation rates were36.99%,10.31%,1.25%,10.5%,4.6%,14.7%respectively. The wide degradation map to organophosphorus pesticides widen the application prospect of strain L19.2. Plasmid pTR102that contained luxAB genes was successfully introduced into malathion-degrading strain L19by electroporation. The light emitting strong activity of strain L19-luxAB. The luxAB gene was expressed in the transformant strain L19-luxAB, and after continual transfer for15generations the characteristic of luminescence was still stable. And the degradation of malathion is no significant difference between L19and L19-luxAB. Strain L19-luxAB can be used to detect the microorganism in soil.3. Strain L19-luxAB could colonize stably in sterilized soil and non-sterilized soil after40d, and the colonization trend is similar. There is a rising trend of the number Strain L19-luxAB after inoculate into the sterilized, the number reached1.23×1010CFU/g dry soil, then decreased until smooth. Quantity level was107CFU/g dry soil. inoculate into the non-sterilized soil shows a declining trend until reach balance, quantity level was106CFU/g dry soil. 4. The strain L19has obvious degradation ability of the malathion in soil. The naturally of Malathion half-life is16.7562h in the soil, but the self life Malathion degradation by strain L19in the soil is6.5867h. The residual concentration of experimental group and control group were28mg/kg and56mg/kg respectively in12h. Malathion can be completely degraded by L19in the soil within84h. |
PDF Full Text Request