Purification and Characterization of a Novel Pyrethroid Hydrolase from Aspergillus niger ZD11

The pyrethroid pesticides residues on foods and environmental contamination are a public safety concern. Pretreatment with pyrethroid hydrolase has the potential to alleviate the conditions. For this purpose, a fungus capable of using pyrethroid pesticides as a sole carbon source was isolated from the soil and characterized as Aspergillus niger ZD11. A novel pyrethroid hydrolase from cell extract was purified 41.5-fold to apparent homogeneity with 12.6% overall recovery. It is a monomeric structure with a molecular mass of 56 kDa, a pI of 5.4, and the enzyme activity was optimal at 45 degrees C and pH 6.5. The activities were strongly inhibited by Hg(2+), Ag(+), and rho-chloromercuribenzoate, whereas less pronounced effects (5-10% inhibition) were observed in the presence of the remaining divalent cations, the chelating agent EDTA and phenanthroline. The purified enzyme hydrolyzed various insecticides with similar carboxylester. trans-Permethrin is the preferred substrate.