In-depth biochemical identification of a novel methyl parathion hydrolase from Azohydromonas australica and its high effectiveness in the degradation of various organophosphorus pesticides

Abstract

Organophosphorus pesticides are highly toxic phosphate compounds with the general structure of O = P(OR)3 and threaten human health seriously. Methyl parathion hydrolase from microbial is an important enzyme to degrade organophosphorus pesticides (OPs) into less toxic or nontoxic compounds like.p-nitrophenol and diethyl phosphate. Here, a gene encoding methyl parathion hydrolase from Azohydromonas australica was firstly cloned and expressed in Escherichia coli. The recombinant hydrolase showed its optimal pH and temperature at pH 9.5 and 50 °C. Leveraging 1 mM Mn2+, the enzyme activity was significantly enhanced by 29.3-fold, and the thermostability at 40 and 50 °C was also improved. The recombinant MPH showed the specific activity of 4.94 and 16.0 U/mg towards methyl parathion and paraoxon, respectively. Moreover, A. australica MPH could effectively degrade various of OPs pesticides including methyl parathion, paraoxon, dichlorvos and chlorpyrifos in a few minutes, suggesting a great potential in the bioremediation of OPs pesticides.