| Chlorpyrifos had been widely used in agriculture because of its broad insecticides spectrum and low toxicity.However,pesticide residues had exceeded standards due to irrational drug use.Biodegradable pesticide residues were reliable and effective.The phyllosphere microbiomes fill with functions and can promote plant growth,nitrogen fixation,and degradation of pesticide residues.Most of the chlorpyrifos-degrading bacteria have been isolated from water and soil,and there are few reports on the screening of them in phyllosphere.In this study,chlorpyrifos-degrading bacteria were isolated from vegetable phyllosphere by enrichment culture method to verify the diversity of them in vegetable phyllosphere.The degradation characteristics of Buttiauxella sp.CPF 5,one of the most efficient degradation bacteria,were examined by single factor experiments.Rhodobacter sp.EBL0706,a highly efficient degradation bacterium of chlorpyrifos isolated from the phyllosphere of aquatic plants,was used to search for the enzyme genes related to the degradation of chlorpyrifos by using transcriptome sequencing,and to infer the biological metabolic pathway of chlorpyrifos.The results were summarized as following:1)The chlorpyrifos-degrading bacteria isolated from phyllosphere of cabbage and lettuce were distributed in Rhizobium,Stenotrophomonas,Pseudomonas,Acinetobacter and Buttiauxella.2)The degradation rate of chlorpyrifos at 50·mg·L-1 was 60%when the initial inoculum amount of Buttiauxella sp.CPF 5 was 7.5×109 CFU·mL-1.3)The addition of yeast extract contributed to the growth of CPF 5 and enhanced the degradation of chlorpyrifos with the rate of 94%in 7 days.The optimal conditions were determined to be 32℃,pH 8.6 and yeast extract concentration of 7 mg·L-1.Under the optimal conditions referred to above,the degradation rate of chlorpyrifos reached 97%.4)Twenty-eight enzymes related to chlorpyrifos degradation were screened,including esterase,reductase,monooxygenase,dioxygenase. |
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