Biodiversity of wild strains of Saccharomyces cerevisiae as tool to complement and optimize wine quality

The principal agent in winemaking is the yeast Saccharomyces cerevisiae, which is characterized by a significant strain biodiversity. Here we report the characterization of 80 wild S. cerevisiae strains, isolated from grapes of different varieties in southern Italy, for genetic and technological variability. By PCR amplification with M13 primer a significant polymorphism was recorded and 12 different biotypes were identified among the strains. The specific strain-pattern could be used to follow the dynamics of different biotypes during the fermentation process. The analysis of experimental wines obtained by inoculated fermentations with the 80 strains showed significant differences among the wines. The level of each compound was a function of the strain performing the fermentative process. The main variables for the strain differentiation were the production of acetaldehyde and acetic acid, which ranged from 53 to 282 mg/l and from 0.20 to 1.88 g/l, respectively. Selected strains were tested in fermentation with two different grape musts, yielding experimental wines differing in the levels of secondary compounds and polyphenol content, in function of the interaction grape must composition/yeast strain. This finding has an applicative value for the potentiality of utilizing the resource of strain variability as a tool to individuate suitable starter cultures, which are able to complement and optimize grape quality.