Effects of Beer Adaptation on Culturability of Beer-Spoilage Dekkera/Brettanomyces Yeasts

This study was conducted to evaluate the effects of beer adaptation on the culturability of Dekkera/Brettanomyces yeast strains and to identify a medium well suited for the detection of hard-to-culture Dekkera/Brettanomyces. For this purpose, D. anomala NBRC 0796 T and D. bruxellensis NBRC 1587 were repeatedly subcultured in beer, and the culturability of profoundly beer-adapted Dekkera strains was compared on various agar media. As a result, beer-adapted Dekkera strains exhibited diminished culturability on Dekkera medium, universal beer agar, and potato dextrose agar, and the detection time on these media was extended considerably. In contrast, the culturability of beer-adapted D. anomala NBRC 0796 T and D. bruxellensis NBRC 1587 was relatively less compromised with malt agar. Therefore, beer adaptation of Dekkera/Brettanomyces strains was thought to induce hard-to-culture states on many detection media, and malt agar was found to be more suitable for the detection of beer-adapted DekkeralBrettanomyces strains obtained in this study. In addition, it is suggested that culture conditions should be carefully selected for more comprehensive detection of Dekkera/Brettanomyces strains in the brewing industry.