From yeast to hyphae: Multi-omics analysis of environmental factors reshaping morphology and flavor metabolism in Saccharomycopsis fibuligera

Saccharomycopsis fibuligera is widely enriched in the fermentation environment of Feng-flavor Baijiu. However, as a dimorphic yeast, its morphological characteristics and flavor function remain understudied. This study investigated the impact of environmental factors on the morphology and metabolism of S. fibuligera. The results showed that low water and glucose favored the formation of a yeast morphology, with the aroma dominated by mushroom and musty aroma. Conversely, high moisture, pH 4~7, and high glucose promoted hyphal formation and the accumulation of fruity and sweet aroma compounds. Transcriptomic, proteome, and metabolomic analyses revealed that the hyphal state involved the upregulation of glycolysis, the TCA cycle, oxidative phosphorylation, and fatty acid synthesis. This metabolic profile facilitated the accumulation of higher alcohols (phenethyl alcohol‌ and isoamyl alcohol) and ethyl esters (ethyl acetate, phenethyl acetate, ‌and ethyl octanoate). In contrast, the yeast exhibited enhanced lipid degradation and production of unsaturated fatty acids, driving the synthesis of C8 alcohols (3-octanol, 1-octen-3-ol, and (E)-2-octen-1-ol) and lactones (γ-nonalactone, γ-decalactone, and δ-decalactone). Simulated fermentation verified that the water conditions influence the flavor metabolic of the S. fibuligera in sorghum system. This study reveals how environmental signals regulate S. fibuligera's metabolic network, guiding targeted flavor modulation in fermented foods.