Glucose repression of FLO11 gene expression regulates pellicle formation by a wild pellicle-forming yeast strain isolated from contaminated wine

Abstract

Some wild strains of Saccharomyces cerevisiae form a pellicle on the surface of contaminated wines during the post-fermentation period of wine making. In this study, we found that both pellicle formation and FLO11 expression by a wild pellicle-forming strain of S. cerevisiae isolated from contaminated wine were repressed in a glucose-containing medium. Substitution of the promoter region of FLO11 in the cells with a constitutive promoter caused derepression of pellicle formation in the glucose-containing medium and wine. These findings indicate that glucose repression of the expression of the FLO11 gene, but not the glucose repression of the expression of other glucose-repressed genes, is responsible for the glucose-dependent regulation of pellicle formation by the wild pellicle-forming yeast strain. Furthermore, we found that the wild pellicle-forming strain had the same deletion of the 111-bp repression sequence in the FLO11 promoter as the flor strains commercially used for making sherry-like wines. Based on the results obtained in this study, a new method that would prevent deleterious pellicle formation in wineries is discussed.