Impact of serine and serine synthesis genes on H₂S release in Saccharomyces cerevisiae during wine fermentation

Excessive hydrogen sulfide (H₂S) during fermentation causes undesirable sensory properties in wine. In yeast, serine functions as a precursor in the biosynthesis of S-containing compounds, which facilitates H₂S consumption. To investigate the effect of serine on H₂S 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 H₂S levels, increased levels of intracellular serine levels from SER1 and SER2 overexpression reduced H₂S release through increased consumption of sulfur metabolites. In contrast, SER33 overexpression significantly increased H₂S release, and the metabolites and gene expression profile of the sulfur assimilation pathway indicates that SER33 regulated MET17, which mediated H₂S release. Our study revealed valuable insights on the relationship between serine levels and H₂S release, and may be helpful in understanding the H₂S regulation mechanism in yeast during fermentation.