Immobilized Whole Cell System with Methyl Parathion-Degrading Activity for Organophosphate Insecticide Detection

Abstract

As the result of the extensive use and high contamination of organophosphate (OP) insecticides in agricultural products and the environment, especially in developing countries, a simple and convenient means for OP detection and screening was investigated. Whole cells from the recombinant clone BpGP carrying methyl parathion (MP) degrading, mpdB, gene originating from MP-degrading Burkholderia cepacia and possessing MP-degrading activity were immobilized onto the polystyrene surface of the wells of microtiter plates using adsorption method, followed by cross-linking with glutaraldehyde. The immobilized cells were used as a bio-component for spectrophotometric detection of OP compounds, with MP as a representative insecticide. Scanning electron microscope and cell count analyses revealed highly dense, rod shaped bacterial cells stably attached to the well surface. The system was most stable at 25°C and could be used to detect MP repetitively up to 46 rounds, although it was still active at about 45% until round 100. For MP analysis, the linear range of the system was 2-200 µg/mL and the detection limit was 2 µg/mL. The tests on spiked and real samples were also performed and the results revealed high detection efficiency. This immobilized cell microtiter plate system has a great potential to be utilized as an alternative for OP detection and screening with the advantages of simplicity, stability, ease and convenience for assembly and use, and low cost.