Find in Library

Acid stress is a challenging condition that yeast cells must overcome during fermentation. Enhancing the inherent tolerance of industrial <i>Saccharomyces cerevisiae</i> to organic acid stresses is crucial for increasing fermentation efficiency and reducing economic costs. In a previous study, we constructed a <i>Saccharomyces cerevisiae</i> strain SWY85S with improved tolerance to citric acid stress by modifying the second <i>PEP4</i>-allele. Malic acid is a dominant organic acid in grapefruit, which forms the acidic constituents of wine fermentation mash and finished products. We investigated the malic acid stress tolerance of the strain SWY85S in comparison with that of a strain with one <i>PEP4</i>-allele disrupted and the wild-type strain in this study. Our results revealed that the strain SWY85S demonstrated greater tolerance of malic acid stress, regardless of whether it was cultured with adequate nutrient supplies or under amino acid starvation. Moreover, the strain SWY85S performed remarkably in converting glucose to ethanol during fermentation under malic acid stress. This study provides insights into the role of a vacuolar <i>PEP4</i>-allele coding product in response to environmental stress and the physiological mechanism of yeast to withstand organic acid stress.