Nitrogen sources preferences of non-Saccharomyces yeasts to sustain growth and fermentation under winemaking conditions
Résumé
Wine-related non-Saccharomyces yeasts are becoming more widely used in oenological practice for their ability to confer wine a more complex satisfying aroma, but their metabolism remains unknown. Our study explored the nitrogen utilisation profile of three popular non-Saccharomyces species, Torulaspora delbrueckii, Metschnikowia pulcherrima and Metschnikowia fructicola. The nitrogen source preferences to support growth and fermentation as well as the uptake order of different nitrogen sources during wine fermentation were investigated. While T.delbrueckii and S. cerevisiae strains shared the same nitrogen source preferences, Metschnikowia sp. Displayed alower capacity to efficiently use the preferred nitrogen compounds, but were able to assimilate a wider range of amino acids. During alcoholic fermentation, the non-Saccharomyces strains consumed different nitrogen sources in a similar order as S. cerevisiae, but not as quickly. Furthermore, when all the nitrogen sources were supplied in the same amount, their assimilation order was similarly affected for both S. cerevisiae and non-Saccharomyces strains. Under this condition, the rate of nitrogen source consumption of non-Saccharomyces strains and S.cerevisiae was comparable. Overall, this study expands our understanding about the preferences and consumption rates of individual nitrogen sources by the investigated non-Saccharomyces yeasts in a wine environment.This knowledge provides useful information for a more efficient exploitation of non-Saccharomyces strains that improves the management of the wine fermentation.