Selection and preliminary characterization of β-glycosidases producer Patagonian wild yeasts

Four pre-selected indigenous yeast strains belonging to Candida guilliermondii (V2 and V5), Candida pulcherrima (V6) and Kloeckera apiculata (V9), were used as β-glucosidase (βGL) and β-xylosidase (βXL) sources. The optimization of yeast culture conditions was carried out and the effects of oenological parameters on β-glycosidase activities were evaluated. C. guilliermondii V2 and C. pulcherrima V6 strains were selected. These strains showed intracellular (C. pulcherrima V6) and parietal (C. guilliermondii V2) constitutive βGL and βXL. The enzymatic activities were active at pH, glucose, ethanol and SO2 concentrations usually found in winemaking and they were able to release monoterpenols and alcohols from grape juice glycoside extracts. Additionally, these yeast strains were not able to produce volatile acidity and off flavour. Regional ecological relevance of these species was also discussed. Our results evidence that the selected C. guilliermondii V2 and C. pulcherrima V6 strains have interesting oenological characteristics and allow us to think in their potential application in winemaking.