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

During winemaking Saccharomyces cerevisiae strains are exposed continuously to environmental changes and this microorganism responds modifying its transcriptional profile. Yeast flocculation is considered a social trait that allows the cells to escape from hostile conditions by sedimentation. This behaviour is based on the self-interaction of flocculins, proteins encoded by FLO family genes. These are considered responsible of the facultative-helping type cooperation and were designed as green-beard genes. In order to understand the role of flocculation to stress response, the genome wide expression analysis of a wine flocculent S. cerevisiae F6789A strain and its FLO5 deleted strain (F6789A-Δflo5) were determined, using DNA microarray technology. Results highlighted that F6789A strain showed a shorter lag phase in winemaking condition. The comparison of transcriptomic profiles underlined that, while F6789A-Δflo5 strain seemed engaged in the re-organization of the cell wall and in finding different adhesion ways, F6789A strain presented an up-regulation of genes involved in stress response and higher alcohol production.