The effect of combinations of Fusarium mycotoxins (deoxynivalenol, zearalenone and fumonisin B-1) on growth of brewing yeasts

The interactive effect of combinations of the Fusarium mycotoxins deoxyniva lenol (DON), zearalenone (ZEA) and fumonisin B-1 (FB1) on growth of brewing yeasts was examined. Yeast growth was assessed by measurement of dry weigh t or relative growth, cell number, viability and conductance change of the growth medium using direct and indirect methods. The interactive effect of a combination of these mycotoxins was subject to the ratio of toxins in the mixture and the toxicity of individual toxins on yeast growth. When a comb ination of mycotoxins at low concentration was added into the growth medium , no significant inhibitory effect on growth was observed compared to contr ols. However, when a combination of high concentrations of DON and ZEA whic h individually inhibited yeast growth was examined, the interactive effect was shown to pass from antagonism to synergism depending on the ratio of th e toxins in the mixture. As a synergistic interaction between these Fusariu m mycotoxins was observed only at high concentrations, which were far highe r than would be expected in good quality grain, they are not a concern when related to yeast growth under the brewing conditions studied.