The yeast TUM1 affects production of hydrogen sulfide from cysteine treatment during fermentation

Abstract

The undesirable rotten-egg odour of hydrogen sulfide (HS) produced by yeast shortly after yeast inoculation of grape musts might be an important source of desirable varietal thiols, which contribute to tropical aromas in varieties such as Sauvign-on Blanc. In this study, we observed that Saccharomyces cerevisiae strains produce an early burst of HS from cysteine. Both Δmet2 and Δmet17 strains produce a larger burst, likely because they are unable to utilise the HS in the sulfate assimilation pathway. For the first time, we show that TUM1 is partly responsible for the early production of HS from cysteine. Overex-pressing TUM1 elevated production of HS, whilst its deletion yields only half of the HS. We further confirmed that yeast convert cysteine to HS by analysing growth of mutants lacking components of the transsulfuration pathway. High concent-rations of cysteine overcame this growth block, but required TUM1 Collectively, the data indicate that S. cerevisiae does not convert cysteine to sulfate or sulfite, but rather to sulfide via a novel pathway that requires the action of Tum1p. The findi-ngs of this study may allow the improvement of commercial yeasts through the manipulation of sulfur metabolism that are better suited towards production of fruit-driven styles.

Sulfane Sulfur Compounds as Source of Reappearance of Reductive Off-Odors in Wine

“…Experiments of Huang explored whether sulfane sulfur compounds are involved in cysteine catabolism in Saccharomyces cerevisiae. The presented results suggested the contribution of cysteine persulfide (Cys-S-SH) to the formation of polysulfanes and their presence in wine [37]. The formation of polysulfanes and their role as latent precursors of reductive off-odors became part of the "polysulfide theory".…”

Sulfate transport mutants affect hydrogen sulfide and sulfite production during alcoholic fermentation

“…Given these findings, it would be worthwhile to see whether the EMS mutants that produce excess H 2 S (SJ6‐1, SJ6‐2, D2‐4, D26‐2 and SJ9‐3; Figures S1, S2 and S3) also had enhanced GSH production. Whilst high H 2 S is considered a negative attribute, recent work has shown that it enhances thiol production in CDGJM supplemented with (E)‐2‐hexenal leading to increased 3‐mercaptohexan‐1‐ol (3MH) and 3‐mercaptohexan‐1‐ol acetate (3MHA) production (Huang, 2017).…”

“…Whilst this study focused on low H 2 S producing yeast strains, other researchers have been interested in generating new strains with enhanced GSH production as a means of improving wine aroma. Similar approaches have been used whereby another sulfate toxic analogue, molybdate (IV) or Mo (IV) was used to screen for resistant strains (Mezzetti et al, 2014 shown that it enhances thiol production in CDGJM supplemented with (E)-2-hexenal leading to increased 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexan-1-ol acetate (3MHA) production (Huang, 2017).…”

How copper based grape pest management has impacted wine aroma

“…Given the energetic cost of the H 2 S production, the impact on the global yeast metabolism should be evaluated. Numerous projects and techniques have been launched to mitigate or limit H 2 S production 26,27,37 and despite significant advances in the understanding of the production of this unpleasant gas, none of them investigated how the use of copper may have caused this phenotype. The yeast CUP1 background should be considered when looking for the selection of wine yeast for low H 2 S production.…”