[Study on Pseudomonas sp. WBC-3 capable of complete degradation of methylparathion]

A bacterial strain was isolated from the polluted soil around Shashi Pesticides Factory, which was capable of complete degradation of methylparathion. Through chemotaxonomic characterizations and phylogenetic inference based on 16S rDNA sequence analysis, the strain was identified as a member of the genus and was named as Pseudomonas sp. WBC-3. It can tolerate high-concentration methylparathion up to 800 mg/L in basic medium and up to 2000 mg/L in 0.1% glucose medium. Using 300 mg/L methylparathion as its sole carbon and nitrogen sources, the strain was able to degrade 15 mg of parathion per liter per hour and reached its stationary phase in about 22 hours. The strain possessed broad-spectrum degradative capability to kinds of organophosphorus pesticides and aromatic compounds. Its organophosphate hydrolase was purified from the periplasm of WBC-3 to homogeneity, through a whose process consisting of ammonium sulfate precipitation, Sephadex G-75 gel filtration, Q Sepharose FF ionexchange column chromatography. The purified enzyme showed a single band on SDS-PAGE gel with an approximate molecular weight of 33.5 kD.