Isolation And Characterization Of Lambda-Cyhalothrin Degrading Bacterium

Synthetic pyrethroid insecticides are widely used in prevention and control from agricultureand family pests presently. Residue problem and harm are becoming more and more serious. Asan efficient way to remove pesticides pollution，the biodegradation of pesticides has graduallybecome the hot issue in the field of environmental sciences. Microorganisms play an importantrole in the bioremediation of pesticide residues.By enrichment of soil samples,an effective straincapable of degrading Lambda-cyhalothrin as a sole carbon source was isolated,and its degrada-tive properties were investigated. The results are as follows:（1）Abacterial named F-3which could degrade the insecticide Lambda-cyhalothrin wasisolated from the soil in Tie Guan Yin tea garden of long-term pesticide contamination in Anxiand was identified as Pseudomonas aeruginosa by analyses of morphology,physio-biochemistryfeatures and16S rDNA.（2）The investigation of the biological characteristics and tolerance to Lambda-cyhalothrinof the strain F-3,indicated that pH8.0and30℃were the optimal condition of growth. It took24hours for the strain to start to enter the index period when it was incubated on medium of beef-typetone,and the maximum Lambda-cyhalothrin concentration for the growth of the strain wasfound to be1500mg·L^-1,while it could grow much better at300mg·L^-1and500mg·L^-1.（3）By the shake flask test,the optimal environmental conditions of degradation werestudied,and the results showed that the optimal condition was pH8.0,30℃,inoculated amount at5%,Best substrate concentration500mg·L^-1ml， best ventilation90ml/300ml.The strain F-3could simultaneously degrade Cypermethrin, Fenpropathrin,and the degradation rates were34%and37.54%respectively.These provided favorable conditions for the bioremediation of contam-inated soil. Under this condition, the degradation rate of lambda-cyhalothrin by strain F-3was upto75%.（4）The degradative properties of other pesticides by F-3were studied. The results are asfollows: In optimized conditions, the degradation rate of lambda-cyhalothrin by strain F-3is 80.51%when Lambda-cyhalothrin concentration of100mg·L^-1. The strain F-3could simu-ltaneously degrade Fenpropathrin, cypermethrin, bifenthrin, glyphosate,carbofuran, and thedegradation rates were67.29%，69.70%，45.47%，24.94%and15.69%respectively. whenpyrethroid concentration was200mg·L^-1,the strain F-3could simultaneously degrade Lambda--cyhalothrin,Fenpropathrin, cypermethrin, bifenthrin, glyphosate,carbofuran, and the degrada-tion rates were68.81%，59.16%，61.35%，38.21%，20.62%and11.37%respectively. In thesame pesticide concentration, the degradation ability of Mixed-strain is better than a single strain.This shows that it has a wide range of degradation and it laid a certain foundation for the study ofsoil bioremediation.（5）This is preliminary study on degrading enzyme genes of strain F-3. Strain F-3genomicDNA as a template for amplification of gene, the result show that there is a size of approximate-ly1800bp fragment.