Molecular Cloning and Characterization of a Newly Isolated Pyrethroid-Degrading Esterase Gene from a Genomic Library of Ochrobactrum anthropi YZ-1

A novel pyrethroid-degrading esterase gene pytY was isolated from the genomic library of Ochrobactrum anthropi YZ-1. It possesses an open reading frame (ORF) of 897 bp. Blast search showed that its deduced amino acid sequence shares moderate identities (30% to 46%) with most homologous esterases. Phylogenetic analysis revealed that PytY is a member of the esterase VI family. pytY showed very low sequence similarity compared with reported pyrethroid-degrading genes. PytY was expressed, purified, and characterized. Enzyme assay revealed that PytY is a broad-spectrum degrading enzyme that can degrade various pyrethroids. It is a new pyrethroid-degrading gene and enriches genetic resource. Kinetic constants of Km and Vmax were 2.34 mmol.L-1 21 and 56.33 nmol min(-1), respectively, with lambda-cyhalothrin as substrate. PytY displayed good degrading ability and stability over a broad range of temperature and pH. The optimal temperature and pH were of 35 degrees C and 7.5. No cofactors were required for enzyme activity. The results highlighted the potential use of PytY in the elimination of pyrethroid residuals from contaminated environments.