| In this study, a stable chlorpyrifos-degrading strainβwas screened and isolated from sludge of pesticide production wastewater, which was identified as Stenotrophomonas acidaminiphila through morphological characteristics and 16SrRNA analysis. Plasmid pTR102 that contained luxAB genes was introduced into chlorpyrifos-degrading strainβby electroporation.Transformants Lux-βwere released to different treatments of soil in order to investigate survival condition and degradation of chlorpyrifos which would provide parameters for building genetically engineered microorganism with high efficiency and good stability.The results are as follows.1. Three strains with chlorpyifos-degrading ability were obtained after isolated and screened, the degradation rate of which were 9.3%, 17.7%, 10.1% respectively at 72h when the concentration of chlorpyifos was 10 mg·L-1; The degradation rate were 15.7%, 30.5%, 14.0% separately at 96h under the above concentration.Stranβwas chosen as further research material for the highest degrading rate which would achieve better degrading result when the concentration of chlorpyifos was 10 mg·L-1 and 1g/L peptone was added into degrading system as well as the inoculation rate was 10%. The degradation rate ofβwas 19.95%, 34.54% and 44.52% at 48h, 72h and 96h respectively which was identified as Stenotrophomonas acidaminiphila through morphological characteristics and 16SrRNA analysis.2. Competent cells that made from bacteria solution at early log phase i.e. cultivated for 3.5h and the absorbance value was 0.5 at 600nm were more sensitive to foreign DNA, and the maximum transformation rate was up to 2.73×102 transformants per microgram plasmids DNA when the concentration of the plasmids was 16.5μg/mL with voltage 2.5kV and time 3ms. After transfered in plates with antibiotic or without antibiotic respectively for 10 times, the transformant lux-βstill had the luminescence activity and Km resistance, indicating that the transformant was stable.3. The optimal growth conditions , growth curve and chlorpyifos- degrading rate of Lux-βandβwere determined separately.The optimal growth condition of Lux-βwere as follows: pH6.8, 30℃, whileβstrain grew fastest at 35℃and pH 7.5; There was no difference in the growth trend of Lux-βandβ, the lag phase of both which was between 0-3h and log phase was in the range of 3-12h then entered stationary phase; Lux-βandβthat have cultivated for 12h were took out and used for degrading chlorpyifos, the degradation rate of Lux-βat 48h, 72h and 96h were 46.91%, 59.9%, 83.29% respectively while the degradation rate ofβat 48h, 72h and 96h were 30.89%, 25.36%, 40.32%. The chlorpyrifos-degrading ability of Lux-βwas doubled.4. Non-sterile soil + 20mg·kg -1 chlorpyrifos + Lux-β, sterilized soil + 20mg·kg -1 chlorpyrifos + Lux-β, Non-sterile soil + Lux-β, sterilized soil + Lux-β, Non-sterile soil + 20 mg·kg -1 chlorpyrifos, sterilized soil + 20 mg·kg -1 chlorpyrifos etc.six treatment groups was settled and for the investigation of competence ability and degradation ability of Lux-β. The result indicates that the quantity variation law of Lux-βarose first and decreased later, however decreased slowly in sterilized soil and quickly in non-sterile soil which suggested that native microbes had a significant influence on foreign microbes.The quantity of Lux-βare larger in chlorpyrifos-adding groups than in groups without chlorpyrifos that shows Lux-βcould use chlorpyrifos as nutrient; The degrading rate of chlorpyrifos from highest to lowest are:Non-sterile soil+20 mg·kg -1 chlorpyrifos + Lux-β, sterilized soil+20 mg·kg-1 chlorpyrifos + Lux-β, Non-sterile soil+20 mg·kg -1 chlorpyrifos, sterilized soil+20 mg·kg -1 chlorpyrifos which suggest that microbes play an important role in degrading chlorpyifos and Lux-βhas higher degradation ability than native microbes ,the two of which can generate synergistic effect on degrading chlorpyrifos.
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