Integrated Physiological and Transcriptomic Analyses of Saccharomyces cerevisiae Under Syringaldehyde Stress

Abstract

Simple Summary Renewable ethanol production from plant biomass is limited by inhibitory compounds generated during biomass processing. Syringaldehyde is a lignin-derived compound that reduces yeast fermentation efficiency, but the mechanisms underlying its toxicity and yeast adaptation remain unclear. In this study, we investigated how syringaldehyde affects Saccharomyces cerevisiae by combining fermentation analysis, cellular characterization, and gene expression analysis. We found that syringaldehyde strongly impaired ethanol production while only slightly affecting biomass accumulation, indicating that it primarily disrupted fermentative function rather than causing extensive growth inhibition. Further analyses showed that syringaldehyde induced multiple physiological stress responses, including alterations in cell envelope and increased membrane lipid oxidation. At the molecular level, yeast cells reduced the expression of genes related to protein production and cellular growth, while activating pathways involved in generating cellular reducing power and removing harmful aldehydes. These responses indicate that yeast cells adapt to syringaldehyde stress by reallocating metabolic resources from growth and ethanol production toward cellular protection and detoxification. This study improves understanding of microbial adaptation to lignin-derived aromatic aldehydes and provides insights for developing more robust yeast strains for sustainable bioethanol production.