A high potential organophosphorus pesticide-degrading enzyme from a newly characterized, Pseudomonas aeruginosa NL01

Twenty seven bacterial isolates were obtained from diazinon-treated agricultural soils in North of Iran and amongst them, an isolate was found to grow in the mineral salt agar plates supplemented with diazinon at concentration of 200 mg L −1 as the sole carbon source. The bacterial isolate was identified by 16S rRNA gene sequence as Pseudomonas aeruginosa NL01. A 36 kDa organophosphorus hydrolase (OPH) enzyme, designated as OPH NL07, was purified by DEAE sepharose column chromatography. The purified enzyme showed a single band on SDS-PAGE. The Michaelis constant (Km) and maximal velocity (Vmax) values of enzyme for paraoxon as substrate were 10 µM and 66.67 µM/min, respectively. The effect of pH and temperature on enzyme activity indicated that the OPH NL07 had the highest activity at pH 8 and was active at a range of temperatures from 25 to 60°C, although, optimum temperature for enzyme activity was 37°C. Enzyme activity was enhanced by 1.28 and 1.09 fold in the presence of CoCl2 and CaCl2, each at 2 mM, while addition of ZnCl2, MgCl2, FeCl3, SDS and EDTA, each at 2 mM inhibited the enzyme by 0.93, 0.92, 0.51, 0.06 and 0.00 fold, respectively. The OPH NL07 seems to be suitable as biocatalyst for practical use in bioremediation of organophosphorus pesticides (OPs)-contaminated soils.   Key words: Diazinon, organophosphorus pesticides, organophosphorus hydrolase,Pseudomonas aeruginosa.