Integrated transcriptomic and physiological and biochemical analysis reveal the molecular mechanism of proline regulating the resistance of Saccharomyces cerevisiae to tannic acid stress

Tannic acid has a significant inhibitory effect on the growth and fermentation of Saccharomyces cerevisiae, which in turn affects the quality of fruit wine. Proline is an amino acid that can effectively alleviate stress in S. cerevisiae under environmental stress conditions. This study aimed to evaluate the effects of proline on the fermentation characteristics, cell structure, and gene expression of S. cerevisiae NCUF309.5 under tannic acid stress. The results showed that the growth and ethanol production of S. cerevisiae NCUF309.5 treated with 500 mg/L proline increased by 30 % and 27.87 %, respectively. Additionally, the relative conductivity of the cell membrane of S. cerevisiae NCUF309.5 was significantly reduced (P < 0.05), and the non-specific leakage of macromolecular substances, such as proteins and polysaccharides, was decreased. Transcriptomic analysis revealed that proline upregulated the expression of glycolysis-related genes, thereby increasing ATP production. The upregulation of ribosomal pathway genes helped maintain the stability of protein synthesis and regulate intracellular metabolic balance. Additionally, the up-regulation of ERG1 and ECM22 genes promoted ergosterol synthesis, which in turn maintained the normal physiological function of the S. cerevisiae cell membrane. This research enriches the strategies for producing high-quality fruit wines made from fruits containing high tannic acid, such as grapes and myrtle.