Diversity of Saccharomyces cerevisiae yeasts associated to spontaneously fermenting grapes from an Italian "heroic vine-growing area".

The main aim of this work was to analyse the diversity of wild Saccharomyces cerevisiae isolated from spontaneous fermentations of grapes collected from heroic vine-growing area. A first screening based on several technological traits was used to select 39 strains among 132 isolates. By using three molecular typing techniques (evaluation of cell wall gene polymorphisms, mtDNA restriction analysis, inter-delta amplification analysis) a significant genetic variability was found. The analysis of principal aromatic compounds produced during inoculated fermentation of two grape musts demonstrated the strain impact on wine flavour and a significant influence of grape must on strain metabolic behavior. One selected strain was used in fermentation at cellar level and the analysis of inter-delta region on yeast colonies isolated during the process revealed the high-implantation ability of this strain. The obtained results demonstrate the usefulness of different molecular and technological markers for the evaluation of natural biodiversity among S. cerevisiae strains. This study represents an essential step towards the exploitation and the preservation of biodiversity of strains isolated from heroic vine-growing area. Selected S. cerevisiae strains could represent starter cultures available for winemakers addressed to production of quality premium wines maintaining differential properties of their own area.