Removal of methyl parathion from artificial off-gas using a bioreactor containing a constructed microbial consortium.

Methyl parathion (MP), a highly toxic organophosphorus pesticide, was widely used for agriculture crop protection. During the production of MP and the process of MP-containing wastewater treatment, MP can release into the atmosphere and will do great harm to adjacent communities. A consortium comprised of an engineered microorganism and a natural p-nitrophenol (PNP) degrader was assembled for complete mineralization of MP. We genetically engineered Escherichia coli BL21 (DE3) enabling the overexpression of methyl parathion hydrolase (MPH). In addition, we isolated Ochrobactrum sp. strain LL-1 that utilized PNP, a product of MP hydrolysis, as the sole carbon, nitrogen, and energy source. The coculture effectively hydrolyzed 0.2 mM MP and prevented the accumulation of PNP in suspended culture. A laboratory-scale bioreactor containing the dual-species consortium was developed for the treatment of artificial off-gas containing MP. The bioreactor maintained over 98% of average MP removal efficiency over a 75 day period, and PNP produced from hydrolysis of MP was degraded completely, indicating that complete mineralization of MP was achieved. The strategy of linking degrading consortium to a bioreactor may provide an alternative to physicochemical abatement technologies for the treatment of waste-gas streams containing MP as well as other PNP-substituted organophosphates.