Isolation and degradation characteristics of high effective Cypermethrin-degrading microorganisms from tea garden soil

12 strains of microorganisms which have stronger tolerance to cypermethrin were isolated from tea garden soil samples through step-wise domestication.Among these microorganisms,4 species of bacteria showed high ability to degrade cypermethrin with their degradation rate being over 80%.The identification results showed that one of the bactieria which has stronger tolerance,higher degradability and better stability for cypermethrin is Klebsiella oxytoca.The environment factors have a great impact on cypermethrin degradation rate.It reached the maximum of 83.06% when the strain was incubated in 30 mL mineral medium with 200 mg/L of cypermethrin,inoculum volume of 7% and pH7.5 in a 250 mL conical flask on a rotary shaker(180 r/min) at 35 ℃ for 72 h.