Unveiling the yeast interaction: Insights into the role of Saccharomyces cerevisiae metabolites in regulating Torulaspora delbrueckii aroma biosynthesis during wine fermentation

The interactions between Saccharomyces cerevisiae and non-Saccharomyces yeasts through secreted metabolites play a crucial role in shaping wine aroma profiles, yet the underlying mechanisms remain inadequately understood. This study used a cell/medium separation strategy coupled with transcriptomic and metabolomic analyses to elucidate the influence of S. cerevisiae metabolites on aroma biosynthesis in Torulaspora delbrueckii during wine fermentation. Results demonstrated that S. cerevisiae metabolites inhibited the growth of T. delbrueckii and suppressed the production of several key volatile compounds, including ethyl acetate, ethyl butanoate, and 2-phenylethyl alcohol. Transcriptome analysis revealed significant downregulation of essential genes involved in aroma synthesis pathways in T. delbrueckii, particularly EHT1/EEB1, ARO10, ADH3, HOM2, FAS1, and FAS2. Untargeted metabolomic profiling identified 867 metabolites, with five differentially produced metabolites from S. cerevisiae significantly affecting aroma formation in T. delbrueckii. Notably, adenosine (ADO), glycerophosphocholine (GPC), and 2-hydroxyisocaproic acid (HIA) enhanced the production of ethyl decanoate (237.63 %) and 2-phenylethyl alcohol (29.06 %), while N-octanoylglycine (NOG) increased the production of ethyl octanoate (229.29 %) and octanoic acid (219.36 %). Importantly, indole-3-carboxaldehyde (ICA) exhibited significant inhibitory effects on T. delbrueckii growth and reduced concentrations of most aroma compounds. These findings provide novel insights into the metabolic interactions between yeasts during wine fermentation and offer winemakers strategic approaches for the targeted modulation of wine aromatic characteristics.