Identification and degradation characteristics of a pyrethroid pesticides degrading Achromobacter sp.JZL-3

The degradation characterizatics of pyrethroid pesticidesdegrading bacterium JZL - 3, which was isolated from activated sludge collected from wastewater-treating system of a pesticide manufacturer, was studied. The strain was identified as Arthrobacter sp. according to its physiological biochemical characteristic and the similarity analysis of its 16S rDNA sequence and was able to degrade about 90% cypermethrin (100 mg/L) in 72 hours. Strain JZL - 3 was capable of degrading a wide range of pyrethroid pesticides, including fenpropathrin, permethrin, cypermethrin, fenvalerate, deltamelthrin, cyhalothrin and bifenthrin . Fenpropathrin was the most preferred substrate, permethrin, cypermethrin and fenvalerate were degraded slower than fenpropathrin, while much faster than bifenthrin , cyhalothrin and deltamethrin. Bifenthrin was the most persistent. These results indicated that substitutions of methyl with α-cyano group, dichloroethylene or chloridben had little influence on the degradation efficiencies, while the substitutions of chloroyl with bromovinyl, fluoro, on the chrysanthemic acid and the replacement of the 3-phenoxybenzyl with a biphenyl significantly reduced the degradation efficiencies. The optimal temperature and pH for the degradation was 30℃ and 7.0, respectively. The degradation efficiency was related positively to initial inoculum size (1 % - 5 % ). When the initial inoculum size was more than 7 % , the degradation efficiency was not been effected. The strain could degrade cypermethrin rapidly when initial concentration was 20 ～ 50 mg/L, while the degradation rate was significantly reduced when initial concentration was more than 100 mg/L. No cis-trans isomer selectivity was observed to the biodegradation of permethrin and cypermethrin; this feature is different from reported results. The results of degradation characterizatics to pyrethroid pesticides indicated that strain JZL - 3 has potential use for bioremediation of pyrethroid-contaminated soils and waters.