Investigation of novel metabolites generated by Torulaspora delbrueckii to promote the aroma biosynthesis in Saccharomyces cerevisiae during wine fermentation

The co-fermentation of Saccharomyces cerevisiae and non -Saccharomyces has been recognized as an effective strategy for improving the quality of wine aroma. One of the most critical factors for the aroma enhancement is the yeast-produced metabolites, but the underlying mechanisms remain poorly understood. In this study, we used a cell/medium separation strategy to investigate the effects of metabolites generated by Torulaspora delbrueckii on the aroma biosynthesis in S. cerevisiae . The results demonstrated that T. delbrueckii metabolites enhanced the production of ethyl octanoate, ethyl decanoate, isoamyl acetate, and isopentanol within S. cerevisiae . Upregulation of aroma-related genes, including EEB1 , SLI1 , BAP3 , BAT1 , PDC1 , and PDC5 in S. cerevisiae , was responsible for the aroma enhancement. The untargeted metabolomic analysis determined a total of 869 T. delbrueckii metabolites, in which three novel metabolites were identified to promote the aroma formation in S. cerevisiae . Specifically, 3-amino-4-methylpentanoic acid stimulated the levels of ethyl octanoate (up to 42.55%) and ethyl decanoate (up to 31.92%), while 4-methylaminobutyric acid and citraconic acid increased the production of ethyl hexanoate (up to 59.19%) and isoamyl acetate (up to 32.26%). A comprehensive understanding of the specific yeast metabolites provides a robust foundation for winemakers to purposefully modulate the aromatic characteristics of wines. • Effects of T. delbrueckii metabolites on S. cerevisiae aroma were determined using a cell/medium separation strategy. • Ethyl octanoate, ethyl decanoate, isoamyl acetate, and isopentanol were promoted by T. delbrueckii metabolites. • A total of 869 T. delbrueckii metabolites were found by untargeted metabolomic analysis. • 3-Amino-4-methylpentanoic acid stimulated the production of ethyl octanoate and ethyl decanoate. • 4-Methylaminobutyric acid and citraconic acid enhanced the levels of ethyl hexanoate and isoamyl acetate.