Dynamics of Saccharomyces cerevisiae Strains Isolated from Vine Bark in Vineyard: Influence of Plant Age and Strain Presence during Grape must Spontaneous Fermentations

Abstract

In this study, two vineyards of different age were chosen. During three years, a sampling campaign was performed for isolating vineyard-associated Saccharomyces cerevisiae (S. cerevisiae) strains. Bark portions and, when present, grape bunches were regularly collected from the same vine plants during the overall sampling period. Each bark portion was added to a synthetic must, while each grape bunch was manually crushed, and fermentations were run to isolate S. cerevisiae strains. All collected yeasts were identified at different species and strain levels to evaluate the genetic variability of S. cerevisiae strains in the two vineyards and strains dynamics. Moreover, bark-associated strains were compared with those isolated from spontaneous fermentations of grapes collected during the two harvests. Regarding the youngest vineyard, no S. cerevisiae was identified on bark and grape surface, highlighting the importance of vine age on yeast colonization. Results reported the isolation of S. cerevisiae from vine bark of the old vineyard at all sampling times, regardless of the presence of the grape bunch. Therefore, this environment can be considered an alternative ecological niche that permanently hosts S. cerevisiae. Bark-associated strains were not found on grape bunches and during pilot-scale vinifications, indicating no significative strain transfer from vine bark to the grape must. Commercial starters were identified as well both in vineyards and during vinifications.

Sources and Assembly of Microbial Communities in Vineyards as a Functional Component of Winegrowing

“…The microbiota present on the grape surface at harvest also serve as the initial fermentation consortium present in early wine fermentation. Other plant compartments are unlikely to select for strongly fermentative organisms, as they lack the selective conditions of fruit (namely, low pH and a concentrated source of sugars), but a fair amount of bark and leaves can become intermixed with grapes during harvest and should be thoroughly considered in this discussion as potential reservoirs and vectors for fermentative microorganisms, as recent reports suggest that they could be a reservoir for such microbiota (Morrison-Whittle and Nadai et al, 2019).…”

Fungal Diversity and Dynamics during Grape Wine Fermentations with Different Sulfite Levels and Yeast Inoculations

“…At harvest, the indigenous grape microbiota varies depending on conditions such as weather/climate, relative humidity, grape variety, vineyard management practices, soil composition, and grapevine health and age (Pretorius 2000, Cordero-Bueso et al 2011, Bokulich et al 2014, Pinto et al 2014, Drumonde-Neves et al 2016, Martins et al 2016, Morrison-Whittle et al 2017, Mezzasalma et al 2018, Nadai et al 2019. Fungi colonizing wineries vary depending on vintage, wines produced, and their capacities to adapt and survive the stressful conditions of winery environment (Abdo et al 2020a(Abdo et al , 2020b.…”

Wine Microbial Consortium: Seasonal Sources and Vectors Linking Vineyard and Winery Environments

“…Accordingly, in vineyard soils, where grapes are not left to decay, WMC yeasts were very rare [35,37], explaining their weak incidence when metagenomic techniques are used [53] and rotten grapes are not sampled [49]. On the contrary, the absence of S. cerevisiae in vine bark was not in accordance with other reports [35,[54][55][56]. This contradiction may be explained by the use, in these studies, of an enrichment step essential to recovery of S. cerevisiae present in very low numbers.…”

“…This contradiction may be explained by the use, in these studies, of an enrichment step essential to recovery of S. cerevisiae present in very low numbers. Another explanation may be the uneven and rare presence of yeast populations in vine barks, which may be overcome when a large number of samples is analyzed [54][55][56]. Indeed, Nadai et al [55] did not find S. cerevisiae in young vines, in opposition to those that were 8 years old.…”

“…Another explanation may be the uneven and rare presence of yeast populations in vine barks, which may be overcome when a large number of samples is analyzed [54][55][56]. Indeed, Nadai et al [55] did not find S. cerevisiae in young vines, in opposition to those that were 8 years old.…”