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

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.在酿酒发酵条件下，酵母菌会面临多种胁迫，酿酒酵母（Saccharomyces cerevisiae）菌株可通过调控自身转录程序产生应激响应。酵母菌絮凝是一种社会性群体性状，可使细胞通过沉降作用脱离恶劣环境，该行为主要由基因组中存在的FLO绿胡子（greenbeard）基因所介导。 为探究絮凝在胁迫响应中的生物学功能，本研究将一株絮凝性酿酒酵母葡萄酒菌株及其FLO5基因敲除菌株，分别置于标准发酵与二次发酵体系中培养，并在两种发酵过程的中期开展全基因组表达分析。 研究结果显示，FLO5基因敲除菌株主要通过细胞壁重组寻找替代黏附途径；而絮凝性酵母菌则呈现出蛋白质层面的应激响应，且参与高级醇合成的基因表达量显著上调。 本研究所得数据证实了FLO5在絮凝表型中的关键作用，并凸显了絮凝在胁迫响应中的重要生物学功能。