School of Chemical Sciences, University of Auckland, 23 Symonds St, Auckland, 1142, New Zealand.
School of Chemical Sciences, University of Auckland, 23 Symonds St, Auckland, 1142, New Zealand; School of Biological Sciences, University of Auckland, 3A Symonds St, Auckland, 1142, New Zealand.
Food Microbiol. 2023 Feb;109:104124. doi: 10.1016/j.fm.2022.104124. Epub 2022 Aug 30.
Polysulfide degradation in wine can result in hydrogen sulfide (HS) release, imparting a rotten-egg smell that is detrimental to wine quality. Although the presence of wine polysulfides has been demonstrated, their biogenesis remains unclear. This study investigated the role of Saccharomyces cerevisiae in polysulfide formation during fermentation, with and without 5 mM cysteine supplementation as an HS source. Using an established liquid chromatography-tandem mass spectrometry method, monobromobimane derivatives of hydropolysulfides, including CysSSSH, CysSSSSH and GSSSSH, and two oxidized polysulfides, GSSG and GSSSSG, were detected in yeast cells at the end of fermentation in a grape juice-like medium. Polysulfide production by four S. cerevisiae single deletion mutants (BY4743 Δcys3, Δcys4, Δmet17 and Δtum1) showed no significant differences compared to BY4743, suggesting that uncharacterized pathways maintain cellular polysulfide homeostasis. Five mM cysteine addition increased the formation of shorter sulfur chain species, including GSS-bimane and GSSG, but did not elevate levels of longer sulfur chain species. Additionally, polysulfides with even numbers of sulfur atoms tended to predominate in cellular lysates. Oxidized polysulfides and longer chain hydropolysulfides were not detected in finished wines. This evidence suggests that these polysulfides are unstable in wine-like environments or not transported extracellularly. Collectively, our data illustrate the complexity of yeast polysulfide metabolism under fermentation conditions.
葡萄酒中的多硫化物会降解产生硫化氢（HS），从而产生腐蛋气味，对葡萄酒的质量造成损害。虽然已经证明了葡萄酒多硫化物的存在，但它们的生物合成仍然不清楚。本研究调查了酿酒酵母在发酵过程中形成多硫化物的作用，有无 5 mM 半胱氨酸作为 HS 源。使用建立的液相色谱-串联质谱法，在葡萄汁样培养基中发酵结束时，从酵母细胞中检测到氢多硫化物的单溴化亚胺衍生物，包括 CysSSSH、CysSSSSH 和 GSSSSH，以及两种氧化多硫化物 GSSG 和 GSSSSG。与 BY4743 相比，四个酿酒酵母单缺失突变体（BY4743 Δcys3、Δcys4、Δmet17 和 Δtum1）的多硫化物产生没有显著差异，这表明存在未被表征的途径来维持细胞内多硫化物的平衡。添加 5 mM 半胱氨酸会增加短硫链物种的形成，包括 GSS-亚胺和 GSSG，但不会提高长硫链物种的水平。此外，细胞裂解物中偶数个硫原子的多硫化物往往占优势。氧化多硫化物和更长链的氢多硫化物在成品葡萄酒中未被检测到。这表明这些多硫化物在类似葡萄酒的环境中不稳定或不被运出细胞外。总的来说，我们的数据说明了在发酵条件下酵母多硫化物代谢的复杂性。
