Effect of Temperature on the Prevalence of Saccharomyces Non cerevisiae Species against a S. cerevisiae Wine Strain in Wine Fermentation: Competition, Physiological Fitness, and Influence in Final Wine Composition

Abstract

Saccharomyces cerevisiae is the main microorganism responsible for the fermentation of wine. Nevertheless, in the last years wineries are facing new challenges due to current market demands and climate change effects on the wine quality. New yeast starters formed by non-conventional Saccharomyces species (such as S. uvarum or S. kudriavzevii) or their hybrids (S. cerevisiae x S. uvarum and S. cerevisiae x S. kudriavzevii) can contribute to solve some of these challenges. They exhibit good fermentative capabilities at low temperatures, producing wines with lower alcohol and higher glycerol amounts. However, S. cerevisiae can competitively displace other yeast species from wine fermentations, therefore the use of these new starters requires an analysis of their behavior during competition with S. cerevisiae during wine fermentation. In the present study we analyzed the survival capacity of non-cerevisiae strains in competition with S. cerevisiae during fermentation of synthetic wine must at different temperatures. First, we developed a new method, based on QPCR, to quantify the proportion of different Saccharomyces yeasts in mixed cultures. This method was used to assess the effect of competition on the growth fitness. In addition, fermentation kinetics parameters and final wine compositions were also analyzed. We observed that some cryotolerant Saccharomyces yeasts, particularly S. uvarum, seriously compromised S. cerevisiae fitness during competences at lower temperatures, which explains why S. uvarum can replace S. cerevisiae during wine fermentations in European regions with oceanic and continental climates. From an enological point of view, mixed co-cultures between S. cerevisiae and S. paradoxus or S. eubayanus, deteriorated fermentation parameters and the final product composition compared to single S. cerevisiae inoculation. However, in co-inoculated synthetic must in which S. kudriavzevii or S. uvarum coexisted with S. cerevisiae, there were fermentation performance improvements and the final wines contained less ethanol and higher amounts of glycerol. Finally, it is interesting to note that in co-inoculated fermentations, wine strains of S. cerevisiae and S. uvarum performed better than non-wine strains of the same species.

Keywords: Saccharomyces species; competition; fitness; temperature; wine composition; wine fermentation.

Figure 1

Scheme used for QPCR primers design.

Figure 2

Calculated relative quantification by QPCR against theoretical values. Boxplot shows the summary of all the data, while small graphics show the dispersion for each specific pair of primers. Data sets were adjusted to a linear model. Dotted lines represent normal distribution and full lines denote adjustments.

Figure 3

Presence of both strains from each competition when their highest cell densities were reached. Values are the mean of three replicates. Error bars represent SD.

Figure 4

Relative intrinsic growth rate (RΔr = (r_competition − r_single)/r_single) caused by the effect of competitions between Saccharomyces cerevisiae T73 and S. paradoxus 54 (A), S. cerevisiae T73 and S. eubayanus NPCC1292 (B), S. cerevisiae T73 and S. uvarum BMV58 (C), S. cerevisiae T73 and S. uvarum CECT12600 (D), S. cerevisiae T73 and S. kudriavzevii CR85 (E), and S. cerevisiae YPS128 and S. kudriavzevii CR85 (F). Values are the means of triplicate experiments. Error bars represent SD.

Figure 5

Comparative of performance in competition and growth kinetics parameters in single culture for S. cerevisiae (A) and competitor strains (B).