Different genetic responses to oenological conditions between a flocculent wine yeast and its FLO5 deleted strain: insights from the transcriptome. Saccharomyces cerevisiae

In oenological conditions, yeasts are exposed to several stresses and Saccharomyces cerevisiae strains respond modifying their transcriptional program. Yeast flocculation is a social trait that permits to the cells to escape to hostile conditions by sedimentation. This behaviour is mainly due to the presence in the genome of FLO greenbeards genes. In order to understand the role of flocculation in stress response a flocculent S. cerevisiae wine strain and his FLO5 deleted strain were submitted to standard and second fermentation. At the middle of these two processes a genome wide expression analysis was performed. Results showed that while the FLO5 deleted strain was engaged to a re-organization of cell wall and to find a different way to adhere, flocculent yeast presented a proteic stress response and an up-regulation of genes involved in superior alcohols production. Obtained data confirmed the importance of FLO5 in flocculation phenotype and highlight the role of flocculation in stress response. Overall design: Two independent experiments were performed with yeasts at 45 g CO2/L release. For each experiment, two different strains F6789 and F6789Deltaflo5 growing on sparking wine medium (SW) or synthetic medium (SM) were compared.