Isolation,screeningandapplicationpotentialevaluationofdeltamethrin-degradingmicroorganism

In order to solve the problem of residual contamination caused by the extensive use of deltamethrin and enrich the resource library of deltamethrin-degrading microorganisms, the effective deltamethrin-degrading XQ08 strain was isolated by enrichment culture method. The strain XQ08 was identified as Stenotrophomonas maltophilia based on the morphological, physiological and biochemical characteristics, and the 16S rDNA homologue sequence analysis. The results showed that the strain XQ08 could degrade more than 66.76% of 50 mg/L deltamethrin in pure cultures within 5 d. Moreover, the ideal fermentation effect of the strain XQ08 could be achieved under the conditions of 35 ℃, pH 8.0, maltose as a carbon source and ammonium chloride as a nitrogen source. And fermentation 24 h OD₆₀₀ could reach 2.5. The optimal preparation technology of the liquid microbial agent of the strain XQ08 was developed. Under the condition of in door pot and field experiments, the XQ08 liquid microbial agent was sprayed on Coriandrum sativum at 2, 24 and 48 h after the spray of 25 g/L deltamethrin EC at a dose of 6.25 a.i.g/hm². The application of the liquid agent of the strain XQ08 could effectively degrade or remove deltamethrin residues on C.sativum. At 3, 5 and 7 d after the application of XQ08 microbial agent, the degradation rate of deltamethrin residues on C. sativum were more than 20%, 50%, 60% and 70%, respectively. 7 and 9 d after the application of the liquid agent of the strain XQ08, the deltamethrin residues on the leaves of C. sativum were lower than 0.5 and 0.2 mg/kg, respectively. This is the first report on the degradation of deltamethrin by S. maltophilia. The degradation pattern of deltamethrin on C. sativum was found to follow first-order kinetics. The results presented here indicate that the strain XQ08 could effectively reduce or eliminate deltamethrin residues on vegetables. The strain XQ08 has attractive application potentia and value for further development.