Isolation,identification and degradation characteristics of a Pseudomonas diminuta strain able to degrade pyrethriod pesticides

A bacterial strain labeled M5R14 was isolated from the sludge in the watercourse of the Pesticide Factory of Hangzhou,and was identified as Pseudomonas diminuta.The strain showed highly efficient degradation of bifenthrin,fenpropathrin and cypermethrin.The physiological characteristics of the strain were investigated,and the bacterium is a gram-negative aerobic coccibacillus,of size 0.3～0.7 μm,which is capable of utilizing bifenthrin,fenpropathrin and cypermethrin as sole carbon sources.The degradation of bifenthrin,fenpropathrin and cypermethrin by strain M5R14 was highest under the conditions of aeration,30℃,inoculation to OD415nm=0.2,pH 6.0～7.0,pesticide concentration 100 mg·L-1 and shaking speed 180 r·min-1.Under such conditions,in culture medium with 100 mg·L-1 bifenthrin,fenpropathrin and cypermethrin together,the degradation ratios are 43.78%,43.91% and 43.75% after incubating for 3 days.Furthermore,the degradation processes fit a first-order kinetic equation and the half lives(t1/2) were 97.6,106.6 and 101.9 h,respectively.The ability of Pseudomonas diminuta M5R14 to degrade bifenthrin,fenpropathrin and cypermethrin is positively correlated to the amount of inoculum,shaking speed and aeration.