Response of fermentative yeasts to trichothecene mycotoxins

Abstract

The effect of T-2, HT-2 and diacetoxyscirpenol (DAS) on growth and fermentation in Kluyveromyces marxianus was examined. Both T-2 and DAS were inhibitory to aerobic growth of this yeast; there was an inverse linear relationship between toxin concentration and the dry mass of cultures, with sensitivity to T-2 being approx. 13 times that to DAS. At a concentration of 5μg T-2/ml culture medium caused reduction in viability of cells relative to controls in both K. marxianus and Saccharomyces cerevisiae within 3h, but by 6h there was marked recovery of viability in S. cerevisiae. With 5μg HT-2/ml, there was only slight retardation of growth at 3h, and recovery or stimulation of growth by 6h. A trend to increasing cell-size with exposure to increasing T-2 concentration was evident by 4h, and by 24h was pronounced in both mother cells and single cells in actively budding cultures. In fermentations of glucose-amended malt extract broth containing up to 5μg T-2/ml there was a concentration-dependent lag before attenuation of fermentable sugars and production of ethanol was measurable, but thereafter the rate of fermentation was similar to controls. As in earlier work with S. cerevisiae, DAS had less effect than T-2 on fermentation.