Studies on acid resistance mechanism of Saccharomyces cerevisiae HJ-U17 during fruit fermentation with high acidity

In recent years, the wine industry has demonstrated an increasing preference of fruits having high acidity. To enhance fermentation capacity and improve the quality of fruit wines, it is crucial to select Saccharomyces cerevisiae that are resistant to acidity and understand their mechanisms of acid resistance. The present study employed mutagenesis to obtain the wine yeast strain S . cerevisiae HJ-U17, which demonstrated favorable fermentation during the processing of high acidity sea buckthorn raw materials. The acid resistance mechanism underlying its performance was elucidated through comprehensive analysis encompassing cellular physiology and omics approaches. Our findings revealed a positive correlation between acid tolerance and factors such as cell membrane integrity, unsaturated fatty acid content, superoxide dismutase activity, and catalase activity. Conversely, acid tolerance showed a negative correlation with reactive oxygen species content. Transcriptomic data analysis unveiled enhancements in energy metabolism, fatty acid chain elongation, synthesis of palmitoleic acid and oleic acid, amino acid metabolism, oxidative stress response, and cell wall remodeling as the level of acid tolerance improved. Additionally, the participation of autophagy further augmented the strain's ability to withstand acidity. This study laid a foundation for the application of acid-resistant S . cerevisiae as the starter of fruit wine with high acidity.