Impact of serine and serine synthesis genes on HS release in Saccharomyces cerevisiae during wine fermentation.

Excessive hydrogen sulfide (HS) during fermentation causes undesirable sensory properties in wine. In yeast, serine functions as a precursor in the biosynthesis of S-containing compounds, which facilitates HS consumption. To investigate the effect of serine on HS release and the underlying mechanism, extracellular and intracellular serine levels were separately increased under fermentation conditions. The results show that, although the abundance of extracellular serine was ineffective in decreasing HS levels, increased levels of intracellular serine levels from SER1 and SER2 overexpression reduced HS release through increased consumption of sulfur metabolites. In contrast, SER33 overexpression significantly increased HS release, and the metabolites and gene expression profile of the sulfur assimilation pathway indicates that SER33 regulated MET17, which mediated HS release. Our study revealed valuable insights on the relationship between serine levels and HS release, and may be helpful in understanding the HS regulation mechanism in yeast during fermentation.