A quick screening method to identify β-glucosidase activity in native wine yeast strains: application of Esculin Glycerol Agar (EGA) medium

Abstract

One hundred and fifty-four yeast strains were isolated from grapes and musts of Uruguayan vineyards and wineries. Only thirty strains showed b-glucosidase activity in Esculin Glycerol Agar (EGA) solid medium. Twenty-one were non-Saccharomyces and nine were Saccharomyces cerevisiae strains. The objective of this study was to evaluate the suitability of Esculin Glycerol Agar (EGA) solid medium for screening b-glucosidase activity in native yeasts strains. Halo sizes measured in the EGA solid medium were correlated to the Glycosyl-Glucose (GG) indexes measured after fermentation of grape musts with each strain. The two S. cerevisiae strains with the best performance were selected for further fermentations on a Muscat Miel grape must, rich in bound monoterpenes. The levels of free linalool, hodiol I and geraniol increased significantly as compared to fermentation with a commercial wine yeast strain. These results show the suitability of this simple and economic medium to identify S. cerevisiae glucosidase producers with a potential impact on real winemaking conditions. On the other hand, great variability was found for the non-Saccharomyces strains, and this would demand further studies for each species. In conclusion, the use of EGA solid medium shows that the screening method is suitable for exploring the glucosidase activity of native strains of S. cerevisiae and shows good correlation with its real impact on free aroma compounds in the final wine.

Autochthonous yeasts with β-glucosidase activity increase resveratrol concentration during the alcoholic fermentation of Vitis labrusca grape must

“…Although arbutin and esculin derivatives were the most reliable β-glucosidic grape analogues, no studies have correlated these assays with the natural grape glucosides hydrolysis capability by wine-related yeasts (Pérez et al, 2011), as the piceid substrate.…”

“…Pérez et al (2011) showed that it is important to create collections of native wine yeasts, since very few strains with β-glucosidase activity have been identified. In fact, the above restricts knowledge of their winemaking potential.…”

“…Since only few strains of Saccharomyces cerevisiae possess β-glucosidase activity, recent studies have focused on indigenous species of non-Saccharomyces strains to impart special characteristics to the wines Domizio et al, 2011;Hong & Park, 2013). The lack of screening methods for glucosidase activity which are able to correlate with real winemaking conditions is one of the limitations to identify proper wine-related β-glucosidase-producer yeasts (Pérez et al, 2011).…”

Selection of Autochthonous Saccharomyces cerevisiae Strains as Wine Starters Using a Polyphasic Approach and Ochratoxin a Removal

“…The following enzymatic activities were assessed: P-D-glucosidase (16,19,25,35), pectolytic and xylanolytic activities (7), protease (44), ester hydrolase and glycosidase (16), and (3-D-xylosidase (25). (3-D-Glucosidase, pecto lytic, and xylanolytic activities were also studied at wine pH and wine ethanol concentration.…”

Use of Saccharomyces cerevisiae strains endowed with β-glucosidase activity for the production of Sangiovese wine

“…b-glucosidase activity of some S. cerevisiae strains has been detected during winemaking indicating the potential of the starter culture to improve the sensorial profile of wine (Hernàndez et al 2003;Tosi et al 2009). The great diversity of S. cerevisiae strains in grapes and wines is well documented and some screening methods for glucosidase activity able to correlate with real wine conditions were recently proposed (Perez et al 2010).…”