AUTHOR=Gobert Antoine , Tourdot-Maréchal Raphaëlle , Morge Christophe , Sparrow Céline , Liu Youzhong , Quintanilla-Casas Beatriz , Vichi Stefania , Alexandre Hervé 

TITLE=Non-Saccharomyces Yeasts Nitrogen Source Preferences: Impact on Sequential Fermentation and Wine Volatile Compounds Profile

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.02175

DOI=10.3389/fmicb.2017.02175

ISSN=1664-302X

ABSTRACT=<p>Nitrogen sources in the must are important for yeast metabolism, growth, and performance, and wine volatile compounds profile. Yeast assimilable nitrogen (YAN) deficiencies in grape must are one of the main causes of stuck and sluggish fermentation. The nitrogen requirement of <italic>Saccharomyces cerevisiae</italic> metabolism has been described in detail. However, the YAN preferences of non-<italic>Saccharomyces</italic> yeasts remain unknown despite their increasingly widespread use in winemaking. Furthermore, the impact of nitrogen consumption by non-<italic>Saccharomyces</italic> yeasts on YAN availability, alcoholic performance and volatile compounds production by <italic>S. cerevisiae</italic> in sequential fermentation has been little studied. With a view to improving the use of non-<italic>Saccharomyces</italic> yeasts in winemaking, we studied the use of amino acids and ammonium by three strains of non-<italic>Saccharomyces</italic> yeasts (<italic>Starmerella bacillaris, Metschnikowia pulcherrima</italic>, and <italic>Pichia membranifaciens</italic>) in grape juice. We first determined which nitrogen sources were preferentially used by these yeasts in pure cultures at 28 and 20°C (because few data are available). We then carried out sequential fermentations at 20°C with <italic>S. cerevisiae</italic>, to assess the impact of the non-<italic>Saccharomyces</italic> yeasts on the availability of assimilable nitrogen for <italic>S. cerevisiae</italic>. Finally, 22 volatile compounds were quantified in sequential fermentation and their levels compared with those in pure cultures of <italic>S. cerevisiae</italic>. We report here, for the first time, that non-<italic>Saccharomyces</italic> yeasts have specific amino-acid consumption profiles. Histidine, methionine, threonine, and tyrosine were not consumed by <italic>S. bacillaris</italic>, aspartic acid was assimilated very slowly by <italic>M. pulcherrima</italic>, and glutamine was not assimilated by <italic>P. membranifaciens</italic>. By contrast, cysteine appeared to be a preferred nitrogen source for all non-<italic>Saccharomyces</italic> yeasts. In sequential fermentation, these specific profiles of amino-acid consumption by non-<italic>Saccharomyces</italic> yeasts may account for some of the interactions observed here, such as poorer performances of <italic>S. cerevisiae</italic> and volatile profile changes.</p>