Wine strains of S. cerevisiae fermenting with/without lipid supplementation

Goal was to identify yeast genes whose expression changed as a function of the presence/absence of lipid nutrients during fermentation of two S. cerevisiae wine strains characterized by a different fermentative behaviour. Cells of Saccharomyces cerevisiae strains EC1118 (commercial strain, Lallemand) and M25 (wild-type strain, University of Sassari culture collection) were precultured at 28°C in orbital shaker in synthetic juice (SJ): glucose 200 g/l; tartaric acid 2 g/l; malic acid 2 g/l; citric acid 0.2 g/l; YNB w/o amino acids and ammonium sulphate 1.7 g/l; ammonium sulphate 2 g/l; pH 3.3. After 24h, cells from precultures were washed twice in sterile water and inoculated in SJ and FSJ (SJ + ergosterol 15 mg/l + oleic acid 15mg/l) to the final concentration of 1,000,000 cells/ml. After 60h, cell samples were harvested, washed in sterile water at 4°C, pelleted and immediately stored in liquid nitrogen for subsequent RNA isolation. Four different conditions, each represented by three biological replicates, were assessed: i) EC1118 in SJ; ii) EC1118 in FSJ; iii) M25 in SJ; iv) M25 in FSJ. This experimental design allowed to discard the influences of strain-specific genetic backgrounds and to consider the differences metabolic responses due to the adaptation to the stress condition tested.