Abstract: Cyfluthrin-degrading strain YC-WZ5 was isolated from the long-term cyfluthrin-contaminated sludge near a pesticide factory by enriched culture. We used physiological properties and 16S rDNA sequence analysis to identify the isolated strain from enriched culture,and used GC to detect the cyfluthrin concentration of the culture in different circumstances. The degrading capacities of the strain under different conditions were studied,and response surface method was used to optimize the conditions for cyfluthrin degradation. The strain YC-WZ5 was identified to be Ochrobactrum intermedium. The 50 mg/L cyfluthrin was fully degraded by YC-WZ5 in 5 days. The conditions for cyfluthrin degradation was optimized as 30.9℃,pH7.16 and 10.9% inoculum size. The degradation rate with different initial concentration of cyfluthrin（100 mg/L,200 mg/L,300mg/L,and 400 mg/L）was 84.5%,54.7%,40% and 30.5% respectively. The degradation rate of cypermethrin,cyhalothrin,deltamethrin and bifenthrin by YC-WZ5 reached 99.83%,91.16%,84.98% and 55.76% respectively at the concentration of 50 mg/L. Conclusively,the strain YC-WZ5 has highly-efficient degradation of cyfluthrin and highly environmental adaptability.

Key words: cyfluthrin, bioremediation, Ochrobactrum intermedium, highly-efficient degradation