Isolation, Identification, and Characterization of Lambda-Cyhalothrin Pesticide Degrading Bacterium ZC-5
A highly efficient lambda-cyhalothrin-degrading bacterium, designated as strain ZC-5, was isolated from the activated sludge of a sewage aeration tank in a pesticide factory by enrichment acclimation and the streak plate method. Strain ZC-5 can grow on minimal medium with lambda-cyhalothrin as the sole source of carbon and nitrogen. After cultivation for 6 h to 24 h, the biomass of the bacterial strain significantly increased at the logarithmic phase. By contrast, the concentration of lambda-cyhalothrin rapidly decreased. The residual lambda-cyhalothrin presented a concentration of 250 mg/L and a degradation rate of 50%. Gas chromatography revealed that this strain can degrade 87.1% lambda-cyhalothrin (500 mg/L) in the culture within 2 days. Morphological analysis showed the Gram-negative strain as short rods. Physiological and biochemical characterizations, as well as phylogenetic analysis of the 16S rDNA sequence identified the bacterium to be an Achromobacter xylosoxidans strain. Results showed that this strain can provide a novel strategy to biodegrade the pesticide lambda-cyhalothrin.