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A colorimetric assay for determination of methyl parathion using recombinant methyl parathion hydrolase
Author(s) -
Anh Dau Hung,
Cheunrungsikul Kritsananporn,
Wichitwechkarn Jesdawan,
Surareungchai Werasak
Publication year - 2011
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.201000348
Subject(s) - parathion methyl , bromothymol blue , dipstick , chemistry , chromatography , hydrolase , hydrolysis , ph indicator , colorimetry , parathion , biochemistry , pesticide , enzyme , biology , organic chemistry , urine , agronomy
A simple, rapid and sensitive colorimetric dipstick assay for the detection of the organophosphorous insecticide methyl parathion (MPT) residue in vegetables was developed. The assay was based on the hydrolysis of MPT by a recombinant methyl parathion hydrolase ( rec MPH), the encoding gene of which was isolated from Burkholderia cepacia , a soil bacterium indigenous to Thailand. This reaction generates protons leading to a change in pH that correlates with the amount of MPH present. Hence, the pH indicator bromothymol blue was used to monitor the MPH hydrolysis as the associated color changes can be observed by the naked eye. The rec MPH was immobilized on a PVDF membrane to establish a dipstick assay format. The assays could detect MPT residues in spiked vegetable samples at the concentration of 1 mg/L without using analytical instrumentation. The test is reusable and stable for up to 3 months in the absence of any preservatives.