Qualitative and quantitative screening of the β-glucosidase activity in Saccharomyces cerevisiae and Saccharomyces uvarum strains isolated from refrigerated must

The aim of the present work was to screen a pool of 75 yeasts belonging to the species Saccharomyces cerevisiae and Saccharomyces uvarum in order to select the strains endowed with β-glucosidase activity. The first screening was a qualitative assay based on chromogenic substrates (arbutin and esculin). The second screening was the quantitative evaluation of the β-glucosidase activity via a p-nitrophenyl-β-d-glucopyranoside assay. The measurement was performed on three different cell preparations, including the extracellular compartment, the cell lysates and the whole cells. This study pointed out the high frequency of β-glucosidase activity in S. uvarum strains. In particular, we retrieved three promising S. uvarum strains, CRY14, VA42 and GRAS14, featuring a high enzymatic activity, exploitable for winemaking. Significance and Impact of the Study: In yeasts, β-glucosidase activity has been extensively described, especially in non-Saccharomyces species, while there is only little evidence of this activity in strains belonging to the Saccharomyces species. In winemaking, β-glucosidase plays essential roles in the hydrolysis of glyco-conjugated precursors and the release of active aromatic compounds. This study provides new insights into the β-glucosidase activity in strains belonging to Saccharomyces cerevisiae and Saccharomyces uvarum species, which are the most important strains in wine industry. Our results point out a marked enzymatic activity for the tested S. uvarum strains. These strains could be exploited for their potential ability to enhance the aroma profiles of wine. In addition, they could be potential sources for the commercial production of enzymes to be applied in winemaking.