A colorimetric technique for detecting trichothecenes and assessing relative potencies

Abstract

We tested a novel colorimetric toxicity test, based on inhibition of beta-galactosidase activity in the yeast Kluyveromyces marxianus, for sensitivity to a range of mycotoxins. A variety of trichothecene mycotoxins could be detected. The order of toxicity established with this bioassay was verrucarin A > roridin A > T-2 toxin > diacetoxyscirpenol > HT-2 toxin > acetyl T-2 toxin > neosolaniol > fusarenon X > T-2 triol > scirpentriol > nivalenol > deoxynivalenol > T-2 tetraol. The sensitivity of detection was high, with the most potent trichothecene tested, verrucarin A, having a 50% effective concentration (concentration of toxin causing 50% inhibition) of 2 ng/ml. Other mycotoxins (cyclopiazonic acid, fumonisin B1, ochratoxin A, patulin, sterigmatocystin, tenuazonic acid, and zearalenone) could not be detected at up to 10 micrograms/ml, nor could aflatoxins B1 and M1 be detected at concentrations up to 25 micrograms/ml. This test should be useful for trichothecene detection and for studies of relevant interactions-both between trichothecenes themselves and between trichothecenes and other food constituents.

FIG. 1

Inhibition of growth and β-galactosidase activity in K. marxianus by trichothecene mycotoxins. Standard deviations for all data points are <10% the value of the point. (A and B) Inhibition of growth (A) and β-galactosidase activity (B) of K. marxianus by VER (○), ROR (●), T-2 (▴), HT-2 (▵), AcT-2 (■), NEO (□), TRI (X), and TET (I). (C and D) Inhibition of growth (C) and β-galactosidase activity (D) of K. marxianus by DAS (●), SCR (○), FUS (▴), NIV (⧫), and DON (□).