Screening of Beta-glucosidase activity in wine yeasts isolated from Cuyo viticulture region of Argentina

MATURANO Y.P.,; RODRIGUEZ L.; TORO M.E.,; VAZQUEZ F.; CASTELLANOS DE FIGUEROA, LUCÍA INÉS

Kiev, Ukraine

Congreso; 12th International Congress on Yeasts (ICY-2008); 2008

Screening of β-glucosidase activity in wine yeasts isolated from Cuyo viticulture region of Argentina Maturano Y. (1), Rodriguez L. (1), Toro M. (1), Vazquez F. (1) & Lucía IC de Figueroa (2, 3)* 1- Instituto de Biotecnología-Universidad Nacional de San Juan, San Juan, Argentina. 2- PROIMI – CONICET. Av. Belgrano y pje. Caseros, San Miguel de Tucumán, Tucumán, Argentina. 3- Universidad Nacional de Tucumán, Facultad de Bioquímica, San Miguel de Tucumán, Tucumán, Argentina Wine aroma is the outcome of a complex interaction among the substance from the grapes, those produced during fermentation, and those arising during aging. Terpenes, one of the major grape components, are hydrolyses during winemaking process caused by enzymes from the grapes themselves or from the microorganisms taking part in the process. β-Glucosidase hydrolyze aroma precursors bound to the sugar molecule contributing to the varietal character of wines. Autochthonous yeasts with β-Glucosidase activity are desirable for using in mixed cultures of Saccharomyces cerevisiae. The aim of this work was to study the β-glucosidase activity of 156 isolated yeasts (45 non-Saccharomyces and 111 Saccharomyces sp.). Qualitative assay was carried out on plates with arbutin as substrate, at 25ºC, pH 4.0 and 6.5 during 72h, in order to select yeasts having β-glucosidase activity. After that those isolates were grown aerobically using an inductive medium containing in g/l: YNB 1.7; (NH4)2 SO4 5; YE 5; peptone 5 and glucose 5 for 72 h. β-glucosidase activity was tested on: culture cell free supernatant, resuspended cells in CP buffer, and crude intracellular extract, using p-nitrophenyl-β-D-glucopyranoside (pNPG) as chromogenic substrate and incubated at 30ºC for 1 h. When a dark halo appeared around colonies on the plates containing arbutin, the results were considered as positive. 38 yeasts were able to hydrolyze arbutin under both pH conditions. 63.15 and 60.5% of non-Saccharomyces grew at pH 6.5 and 4.0, respectively. Highest activity on resuspended cells represented 42%, and the major activity on the cell free supernatant was positive in 12 isolates (3 Saccharomyces and 9 non-Saccharomyces). This study clearly revealed the potential of indigenous yeasts to produce useful enzymes to catalyze desired biotransformations during wine fermentation.