Yeasts from organic or biodynamic grapes: genomic and proteomic identification

Introduction: Wines have been traditionally produced by natural fermentations caused by the development of yeasts and lactic acid bacteria originating from the grapes and winery equipment, hence the wine quality is closely related to the microbial ecology of grape and fermentation as well as to the used of selected strains to guide the winemaking. The importance of microbial species that develop during fermentation determine the types and concentrations of many substances that may contribute to the good fermentation, aroma and flavor characteristics, and also the safety of wine. Results and Discussion: The main goal of this study was to characterize the yeast populations of grape musts produced from biodynamic or organic agriculture by two approaches: genomics and proteomics. The suitability of MALDI-TOF-MS Biotyper for the identification of non-clinical samples was verified. The genomics was performed by using PCR reaction (Sanger sequencing) with the amplification of ITS region and the proteomics was carried out through MALDI-TOF-MS Biotyper. About 130 isolated strains from fermenting must were identified and both MALDI-TOF MS Biotyper and sequencing showed a more complex yeast population of spontaneously fermented products compared to driven fermentation. The sequencing identified all the tested strains while the MALDI TOF MS Biotyper identified up to the 70-80% of the isolated yeasts, probably due to the incomplete libraries of the instruments. Indeed, this study could support the widening of the libraries with peptide profiles of food interest microorganisms in order to increase the potential applications of the proteomic approach currently limited to clinical areas.