Abstract
Saccharomyces cerevisiae populations occurring in spontaneous wine fermentations display a high polymorphism, although few strains are generally able to dominate the fermentative process. Recent studies have suggested that these indigenous S. cerevisiae strains are representative of a specific oenological ecosystem, being associated to a given wine-producing area or a single winery. In contrast, according to other ecological studies, no correlation between genotypic and phenotypic groups of the native S. cerevisiae strains and their origin was found. In this work, several S. cerevisiae strains were isolated in consecutive years from spontaneous fermentations carried out in the same wineries located in different oenological areas in Tuscany, and their persistence was assessed by molecular methods. Some predominant S. cerevisiae strains persisted in different fermentations in the same winery from one year to another and they seemed to be representative of a single winery rather than of an oenological area. Therefore, data suggested the idea of the “winery effect” or a microbial terroir at a smaller scale. The use of these typical strains as starter yeasts could provide wines with the distinctive characteristics of a particular winery or sub-zone.
Highlights
The aim of this work was to study the genetic diversity of S. cerevisiae populations in spontaneous alcoholic fermentations carried out during consecutive vintages in four wineries in Tuscany region (Italy), in order to assess the occurrence and the persistence of yeast strains, which were typical of the winery or zone they came from
The biodiversity of S. cerevisiae populations was assessed in spontaneous wine fermentations carried out in consecutive vintages of four wineries, located in three winemaking areas within DOCG or DOC appellations in Tuscany (Italy), with the aim of evaluating the occurrence and the persistence of some yeast strains, which were typical of the winery or the zone they came from
Considering the frequency of different S. cerevisiae strains within each winery in the various vintages, showed one or two predominant strains occurring at high frequencies (>25%), in association with a variable number of secondary strains at low frequencies (
Summary
Saccharomyces cerevisiae yeast, due to its higher alcohol tolerance and other factors responsible for its competitive advantage [1,2], is usually the species predominating the process, this occurs at different times, depending mainly on the non-Saccharomyces/S.cerevisiae ratio and the properties of yeast species constituting the non-Saccharomyces population [2].Several studies, by means of various molecular methods, have largely demonstrated that native S.cerevisiae populations display a significant genetic diversity and that different strains are simultaneously or in succession involved during the alcoholic fermentation [3,4,5,6,7]. Ecological studies carried out on spontaneous wine fermentations in different wine-making areas all over the world (Spain, Austria, Greece, France, Italy, etc.) highlighted that certain S. cerevisiae strains may persist in the same winery in consecutive years, be shared among the wineries of different wine-making areas; or else be representative of a specific geographical area [2,11,12,13,14,15,16,17,18,19] These strains are better adapted to specific winemaking conditions used in each winery or to the environmental conditions of each oenological area, including climate and agricultural practices, and they could play a key role in determining a distinctive wine’s organoleptic properties. The existence of a “winery effect” and a microbial aspect of terroir has been suggested [5,7,11,20,21], and the selection programs to obtain indigenous S. cerevisiae strains to be used as yeast starter cultures to provide wines with distinctive characteristics of a particular winery or enological area, have been promoted
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