Overexpression of methyl parathion hydrolase and its application in detoxification of organophosphates

Abstract

The coding region of mpd gene corresponding to mature methyl parathion hydrolase (MPH) was heterologously overexpressed in Escherichia coli BL21 (DE3) by using pET expression system. The lactose-induced expression yield of MPH is increased 2-fold compared with IPTG as inducer. Furthermore, it was found that specific activity of MPH increased 48% by reducing the induction temperature to 22 degrees C. The addition of 25 mM lactose at 22 degrees C, the MPH activity of fermentation broth had a specific activity of 1.4 x 10(4) U/mg protein. Plasmid was no significant decrease in the modified medium. The optimal pH and temperature of MPH were 8.0 and 30 degrees C, respectively. Over a period of 5 months, the dried cells showed no significant decrease in the activity of the detoxifying enzymes. The crude enzymes in 50 mM citrate-phosphate buffer (pH 8.0) were able to degrade about 98% of the organophosphate pesticides sprayed on cabbage. The detoxification efficiency was superior to that of the treatments of water, detergent, and a commercially available enzyme product. Additionally, the products of pesticide hydrolysis generated by treatment with the enzyme extract were determined to be virtually nontoxic.

Isolation and characterization of two malathion-degrading Pseudomonas sp. in Egypt

“…were able to degrade fenitrothion over a temperature range of 20-40°C with optimum degradation at 30°C. Yang et al (2008) showed that 30°C is the optimal temperature for heterologous expression of methyl parathion hydrolase enzyme (MPH). They found that 30°C is optimal for the formation of properly folded enzyme and inhibition of ATP-dependent and ATPindependent proteolysis.…”

Isolation of a novel gene encoding a 3,5,6-trichloro-2-pyridinol degrading enzyme from a cow rumen metagenomic library

“…YC-1 (Yang et al 2008), and lactic acid bacteria ). Degradation of organophosphorus pesticides by cultured microorganisms, even at high pesticide concentration, has been reported previously (Liu et al 2005).…”

“…Soil bacteria capable of degrading organochlorinated pesticides have also been reported (Hussain et al 2007;Raina et al 2008;Goswami and Singh 2009). The gene encoding chlorpyrifos or organophosphorus pesticide degrading enzyme was isolated previously (Fu et al 2004;Liu et al 2005;Zhang et al 2006;Yang et al 2008;Cho et al 2009), but this work is the first report of a gene encoding a TCP degrading enzyme.…”

Improving the acidic stability of a methyl parathion hydrolase by changing basic residues to acidic residues

“…Organophosphorus hydrolases (OPH) play important roles in the decontamination of organophosphate pesticides and are useful in the bioremediation of pollution caused by organophosphate pesticides (Dong et al 2005;Yang et al 2008Yang et al , 2010Chu et al 2006Chu et al , 2010Xiao et al 2008). A methyl parathion hydrolase, Ochr-MPH, isolated from Ochrobactrum sp.…”