Zinc is an essential micronutrient that serves as a vital cofactor in multiple metabolic pathways, including the mechanism mediated by IZH (Implicated in Zinc Homeostasis) genes and lipid biosynthesis. Previous studies revealed that Saccharomyces cerevisiae ET008-c54 (WT) exhibited excellent fermentation performance at low pH for acidic fruit wines, with IZH4 identified as a key gene. This study investigated the specific role of IZH4 mediated under Zn²⁺ supplementation in low-pH tolerance, using greengage plum wine as a model. Based on fermentation time and sensory evaluation, the optimal Zn²⁺ supplementation level was preliminarily determined to be 2 mg/L. Further metabolomics and flavoromics confirmed that Zn²⁺ supplementation at 2 mg/L was an effective strategy for enhancing the quality of greengage plum wine. On this basis, the effects of IZH4 deletion on the growth behavior and membrane composition of the WT strain under Zn²⁺ supplementation were evaluated. The experimental findings revealed that the knockout strain WT-ΔIzh4 showed reduced growth at pH 2.5. Regarding the cellular lipid composition, WT-ΔIzh4 exhibited notably reduced levels of unsaturated fatty acids and ergosterol compared to WT, which resulted in less fluid membranes. Zn²⁺ supplementation increased the growth rate by 20.1 % and elevated ergosterol content by 15.2 % compared with WT-ΔIzh4, and further adjusted the ratio of unsaturated to saturated fatty acids to a level comparable to that of the WT strain. These results demonstrated the significant role of IZH4 mediated under Zn²⁺ supplementation in the low pH tolerance of yeast by remodeling the cell membrane structure. This investigation offers fresh insights into the biological function of IZH4 against low pH stress, and allows a better-defined target for subsequent genetic improvement of yeast.

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Journal Article

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Tian T, Yang C, Wu JL, Liu S

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