Survival of inoculated Saccharomyces cerevisiae strain on wine grapes during two vintages

Abstract

Aims: To investigate the influence of a specific ecological niche, the wine grape, on the survival and development of Saccharomyces cerevisiae. Methods and Results: A strain with a rare phenotype was sprayed onto the grape surfaces and monitored through two vintages using a specific indicative medium and analysing the internal transcribed spacer regions in the 5·8S rDNA. During the ripening process, there was a progressive colonization of the surface of the undamaged and damaged grapes by epiphytic yeasts, up to the time of harvest. The damaged wine grapes showed a much greater epiphytic yeast population. However, the inoculated S. cerevisiae strain showed a scarce persistence on both undamaged and damaged wine grapes, and the damaged grapes did not appear to improve the grape surface colonization of this strain. Conclusions: Results indicated that wine grape is not a favourable ecological niche for the development and colonization of S. cerevisiae species. Significance and Impact of the Study: Results of this work are further evidence that S. cerevisiae is not specifically associated with natural environments such as damaged and undamaged wine grapes.

Geographic Origin and Diversity of Wine Strains ofSaccharomyces

“…However, since rotting clusters attract insects and insects are vectors of Saccharomyces, it is not clear if the S. cerevisiae strains present arose from the surface of the fruit or not. Direct inoculation of vineyards with commercial yeasts did not lead to their establishment among the vineyard flora (Comitini andCiani 2006, Valero et al 2005), even when damaged berries were inoculated (Comitini and Ciani 2006). Since the level of inoculation in these studies was much higher than would be predicted from insect vectors, these data support the view that Saccharomyces can be considered a minor resident of the surface of a grape with conditions leading to the seepage of berry components selecting for Saccharomyces proliferation.…”

“…With creation of fermentative conditions upon crushing of the fruit, even more strongly enriching conditions are presented to this microbe. Saccharomyces, initially present below detectable levels in spontaneous grape juice fermentations, will often be found as the dominate species at the end of fermentation, even under aseptic grape cluster harvesting conditions (Comitini andCiani 2006, Valero et al 2005). The population density of Saccharomyces in a winery is often higher than the density in the vineyard, and in the absence of selective pressure the greater number of winery yeast relative to vineyard yeast will lead to a greater contribution to the fermentation itself by the winery residents.…”

Survival of commercial yeasts in the winery environment and their prevalence during spontaneous fermentations

“…Moreover, the dissemination of commercial strains was restricted to short distances and limited periods of time, and it was favoured by the presence of run-oV water [19]. In addition, Comitini and Ciani [5] showed that wine grapes were not a favourable ecological niche for the development and colonization of S. cerevisiae species.…”

Rofecoxib

“…Equipment responsible for retaining yeasts may include stemmer-crushers, pumps, pipes, and fermentation vessels (Martini 1993). The main event affecting yeast diversity on grape berries is its health status (Barata et al 2008), which depends on a variety of factors, including grape variety, degree of maturation, treatment with fungicides, presence of insect vectors, and the climate of the vineyard area (Mortimer andPolsinelli 1999, Comitini andCiani 2006). Grapes brought into the winery during harvest are known to affect the air microflora of the winery (Garijo et al 2008), which may influence the S. cerevisiae populations of spontaneous fermentations.…”