Résumé
Hydrogen sulfide (H2S) is the intermediary step of the sulfur assimilation pathway (SAP), used bySaccharomyces cerevisiae to synthesize sulfur-containing amino acids (methionine and cysteine),fundamental for protein biosynthesis. Despite the high energetic cost of the reduction of sulfate tosulfide, wine yeasts have been reported to produce highly variable and sometimes excessive amounts ofH2S during alcoholic fermentation. In this work we compared the cumulative production of H2S over thewhole alcoholic fermentation process of yeast strains from different genetic groups: wine, flor or oaktrees. We show for the first time that the ecology of S. cerevisiae influences the production of H2S, that ishigher for wine strains in comparison to flor strains, despite their genetic proximity. This production isamplified by the addition of SO2 to the fermentation media, commonly used in winemaking asantioxidant and antiseptic treatment. Given the specific high production of wine strains, in comparison toother different ecological niches, we focus on one genomic trait specific to wine strains: copperresistance. Indeed, the metallothionein protein Cup1, amplified in wine strains as the consequence of theadaptation to the use of copper sulfate as fungicide, contains 13 sulfur atoms/protein, and is among thesulfur-richest yeast proteins of the cells. In addition, the unique amplification of CUP1 observed amongwine strains, might lead to a high requirement of sulfur containing amino acids and thus lead to aderegulation of H2S production. We thus evaluate the relations between the number of copies of CUP1 inthe genome of different strains in relation of their production, and observed a complex pattern. Theconstruction of strains carrying different CUP1 copy number in their genomes enables us to validate someof these patterns