A sensitive bioassay for the mycotoxin aflatoxin B1, which also responds to the mycotoxins aflatoxin G1 and T-2 toxin, using engineered baker's yeast

Li, Xingmin, Millson, Stefan, Coker, Raymond and Evans, Ivor (2009) A sensitive bioassay for the mycotoxin aflatoxin B1, which also responds to the mycotoxins aflatoxin G1 and T-2 toxin, using engineered baker's yeast. Journal of Microbiological Methods, 77. pp. 285-291. ISSN 0167-7012

Abstract

A novel aflatoxin B1 bioassay was created by introducing a Lipomyces kononenkoae α-amylase gene into a strain of S. cerevisiae capable of expressing the human cytochrome P450 3A4 (CYP3A4), and the cognate human CYP450 reductase. This strain and a dextranase-expressing strain were used in the development of a microtitre plate mycotoxin bioassay, which employed methanol as the solvent and polymyxin B nonapeptide as a permeation enhancer. Stable co-expression of the CYP3A4 gene system and of the dextranase and amylase genes in the two bioassay strains was demonstrated. The bioassay signalled toxicity as inhibition of secreted carbohydrase activity, using sensitive fluorimetric assays. The amylase-expressing strain could detect aflatoxin B1 at 2 ng/ml, and was more sensitive than the dextranase-expressing strain. Aflatoxin G1 could be detected at 2µg/ml, and the trichothecene mycotoxin T-2 toxin was detectable at 100 ng/ml.

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