Screening and Enzymatic Evaluation of Saccharomyces cerevisiae Populations from Spontaneous Fermentation of Organic Verdejo Wines

Abstract

Microbial populations in spontaneous winemaking contribute to the distinctiveness and quality of the wines. In this study, molecular methods were applied to 484 isolated yeasts to survey the diversity of the Saccharomyces cerevisiae population in spontaneous fermentations of organic Verdejo grapes. Identification was carried out at strain level for samples from different vineyards correct.and stages of the winemaking process over the course of two vintages, establishing 54 different strains. The number of isolates belonging to each strain was not homogeneous, as two predominant strains represented more than half of the isolates independent of vineyard or vintage. Regarding the richness and abundance, differences among the stages of fermentation were confirmed, finding the highest diversity values in racked must and in the end of fermentation stages. Dissimilarity in S. cerevisiae communities was found among vineyards and vintages, distinguishing representative groups of isolates for each of the populations analysed. These results highlight the effect of vineyard and vintage on yeast communities as well as the presence of singular strains in populations of yeasts. Oenologically relevant enzymatic activities, β-lyase, protease and β-glucanase, were detected in 83.9%, 96.8% and 38.7% of the isolates, respectively, which may be of interest for potential future studies.

Non-Saccharomyces Yeasts from Organic Vineyards as Spontaneous Fermentation Agents

“…It has been previously reported that rainy vintages may increase damage to berries, increasing some species such as oxidative yeasts; however, the effect on microbiota is often not clear, as applying scientific methods is not easy. In our study, the meteorological conditions registered in both vintages [19] showed lower accumulated precipitation during the year in the second vintage; however, the volume of precipitation at harvest months was higher than in the first vintage. According to this data, it is not easy to establish a relationship between climate conditions and microbial diversity described in this study.…”

“…At each fermentation point, yeast isolates obtained as separated colonies were picked up and subsequently analysed. A total of 484 isolates were analysed, establishing 54 different genetic groups of S. cerevisiae that comprised 89% of the isolates [19] and 11% of non-Saccharomyces species (Table S1).…”

“…Despite being a unique and high-quality wine, there is a lack of microbial ecological studies to elucidate the indigenous yeasts that play a part in its regional distinctiveness. Previous studies in our group focused on the diversity of the S. cerevisiae population in spontaneous fermentation of Verdejo wine, highlighting the effect of vineyard and vintage on yeast communities as well as the presence of singular strains for each of the populations analysed [19].…”

Modulation of the Aromatic Profile of Verdejo Wine through Sequential Inoculation of Wickerhamomyces anomalus and Saccharomyces cerevisiae

“…Two S. cerevisiae yeast strains (Sc01 and Sc02) and one non-Saccharomyces yeast strain of the species W. anomalus (Wa) were used in this study. The strains were obtained from previous studies of yeast ecology [24,25]. Briefly, yeasts were isolated during spontaneous fermentation processes of organic Verdejo grapes from the vineyards of the Belondrade Winery (La Seca, Valladolid, Spain), located in the AO Rueda.…”

“…Previous research by our group has focused on the study of the population dynamics of yeasts during spontaneous fermentation of the Verdejo grape variety from organic vineyards from the Appellation of Origin Rueda (AO Rueda, Spain). The results enabled us to select strains of S. cerevisiae and non-Saccharomyces yeasts with potential oenological characteristics of interest to be used in unique or sequential inoculations [24,25].…”