Inhibitory effect of Fusarium mycotoxins on growth of brewing yeasts.: 1.: Zearalenone and fumonisin B1

The Fusarium mycotoxins zearalenone (ZEA) and fumonisin B-1 (FB1) added to the growth medium in low and high concentrations, were investigated as a possible cause of inhibition of growth of Saccharomyces cerevisiae lager and ale strains. Toxic effects were assessed by measurement of dry weight or growth relative to controls, cell number, viability and conductance changes of the growth medium using indirect and direct methods. The Fusarium mycotoxins studied affected growth on brewing yeasts, but the inhibitory effect was dependent on concentration, Low concentrations (0.1-2 mu g/ml) had no significant effect on growth compared to controls. Although high concentrations of both mycotoxins strongly affected growth, the inhibitory effect depended on toxin concentration and type, yeast strain, length of incubation and method used to assess growth. The lowest concentrations of mycotoxin causing significant inhibition on growth of these brewing yeasts were 50 mu g/ml ZEA for both yeast strains, and 10 mu g/ml FB1 for the lager strain and 50 mu g/ml for the ale strain.