Cytosolic Peroxiredoxin <i>TSA1</i> Influences Acetic Acid Metabolism and pH Homeostasis in Wine Yeasts

Acetic acid is a key metabolite in yeast fermentation, influencing wine quality through its role in volatile acidity. In <i>Saccharomyces cerevisiae</i>, acetic acid production involves aldehyde dehydrogenases, primarily Ald6p during fermentation and Ald4p under respiratory conditions. However, the regulatory mechanisms of these enzymes throughout fermentation and how they differ in commonly used strains remain partially unclear. This study explores cytosolic peroxiredoxin Tsa1p as a novel regulator of acetic acid metabolism. <i>TSA1</i> gene deletion revealed strain-dependent effects on acetic acid metabolism and tolerance, showing reduced production and enhanced consumption in the laboratory media. Under respiration, Ald4p-driven acetic acid production, which raises extracellular pH, was mitigated by the absence of Tsa1p. During wine fermentation, <i>TSA1</i> deletion decreased the initial acetic acid surge by downregulating the <i>ALD6</i> transcription and enzymatic activity. These findings establish Tsa1p as a metabolic regulator and a potential target for modulating acetic acid levels to manage volatile acidity and improve wine quality.