Original Research Article
Stefani de Ovalle, Beatriz Bre
The current work is the first report on the isolation and characterization of an extracellular βglucosidases from I. orientalis, isolated from Uruguayan Tempranillo grapes. The extracellular activity reached a maximum after 96h of growth in the presence of 20 g/L of cellobiose. β-glucosidases was purified to homogeneity by anion-exchange chromatography and its biochemical properties were studied. Optimum catalytic activity conditions were 50°C and pH 5.0. The enzyme showed wide substrate specificity and proved to be highly tolerant to the presence of wine-associated inhibitory compounds such as glucose (100 g/L) and ethanol (12%). Immobilization onto silica nano-particles greatly improved enzyme stability at low pH (240-fold) with respect to the soluble biocatalyst. In addition, it is very active on wine glycosides and shows several suitable features suggesting that it is appropriate for the release of wine aroma. The increase in concentration of free norisoprenoids, terpenes and phenols was statistically significant. The release of phenols was particularly noteworthy, especially 4-vinilguayacol which is known to provide curry and clove notes. These results suggest the potential of this new β-glucosidase as an aroma-enhancing enzyme in winemaking.