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Antagonism between Saccharomyces cerevisiae and Williopsis mrakii and significance for mixed yeast alcoholic beverage fermentations

Li, Xiao, Liu, Shao‐Quan
International journal of food science & technology 2016 v.51 no.3 pp. 656-663
Saccharomyces cerevisiae, alcoholic beverages, coculture, ethanol, fermentation, glucose, inoculum, yeasts
This research was carried out to investigate the antagonism between Saccharomyces cerevisiae and Williopsis saturnus var. mrakii. When glucose level was ≥12% (w/v) (potential ethanol ≥7.2% v/v), W. mrakii that was co‐inoculated with S. cerevisiae died early, while W. mrakii alone could not survive in broth with ≥8% (v/v) ethanol. Moreover, when glucose was ≥15% (w/v) (potential ethanol ≥9.0% v/v), higher inoculums of S. cerevisiae induced faster cell decline of W. mrakii; when glucose was ≤2% (w/v), there was no early cell decline of W. mrakii at any inoculum ratio, but there was inoculum ratio‐dependent growth retardation. These results indicate that ethanol was at least one of the factors causing early cell decline of W. mrakii in co‐culture with S. cerevisiae. Further, S. cerevisiae was inhibited when it was inoculated sequentially into a W. mrakii monoculture; the former yeast was also suppressed when it was inoculated into the supernatants of a W. mrakii monoculture. This suggests that S. cerevisiae was sensitive to the mycosin (killer toxin) produced by W. mrakii. These findings have implications for controlling mixed yeast alcoholic beverage fermentations.