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

Huang, Chien Wei, Walker, Michelle E., Fedrizzi, Bruno, Roncoroni, Miguel, Gardner, Richard C. and Jiranek, Vladimir (2016) The yeast TUM1 affects production of hydrogen sulfide from cysteine treatment during fermentation. FEMS Yeast Research, 16 (8). (doi:10.1093/femsyr/fow100).

Abstract

The undesirable rotten-egg odour of hydrogen sulfide (H₂S) 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 Sauvignon Blanc. In this study, we observed that Saccharomyces cerevisiae strains produce an early burst of H₂S from cysteine. Both Δmet2 and Δmet17 strains produce a larger burst, likely because they are unable to utilise the H₂S in the sulfate assimilation pathway. For the first time, we show that TUM1 is partly responsible for the early production of H₂S from cysteine. Overexpressing TUM1 elevated production of H₂S, whilst its deletion yields only half of the H₂S. We further confirmed that yeast convert cysteine to H₂S by analysing growth of mutants lacking components of the transsulfuration pathway. High concentrations 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 findings 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.

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Contributors

Author: Vladimir Jiranek

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