Influence of cultural conditions on sensitivity of brewing yeasts growth to Fusarium mycotoxins zearalenone, deoxynivalenol and fumonisin B₁

The influence of cultural parameters, viz. temperature, inoculum size and growth under shaker or static conditions, on the sensitivity of Saccharomyces cerevisiae lager and ale strains to the presence of low (2 µg ml^-1) and high (100 µg ml^-1) concentrations of the mycotoxins zearalenone (ZEA), deoxynivalenol (DON) and fumonisin (FB₁) was examined. Toxic effects were assessed by measuring relative growth, cell number, viability and conductance change in growth medium, and monitoring cell morphology. Culture conditions appeared to affect sensitivity of yeasts to mycotoxins at 100 µg ml^-1 growth medium, but not at 2 µg ml^-1. For both strains, cultures developing from a lower inoculum concentration were more strongly inhibited than at a higher inoculum level, except for the lager strain grown at 13°C and the ale strain at 25°C in the presence of FB₁. Growth inhibition did not seem to be influenced by inoculum size. Growth temperature was important in sensitivity to the mycotoxins. At 25°C, the ale strain was more sensitive to ZEA and DON than the lager strain, but the lager strain was more sensitive to these two toxins at 13°C than at 25°C. In contrast, at 13°C the lager strain was more sensitive to FB₁ than at 25°C, and at 25°C it was more sensitive than the ale strain. Both strains were more sensitive to DON and ZEA when grown statically than with shaking, but in shake-culture the lager strain was more sensitive to FB₁. © 2002 Elsevier Science Ltd. All rights reserved.