From preparation to application: Mushroom-derived chitosan in wine-making exerts microbial suppression and triggers transcriptomic response of Saccharomyces cerevisiae

The antimicrobial efficacy of fungal chitosan in oenological environments and its specific transcriptional impacts on Saccharomyces cerevisiae during wine fermentation remain insufficiently characterized. In this study, a mushroom-derived chitosan is prepared by sequential chemical treatments including deproteinization, deacetylation, lyophilization and purification. The obtained chitosan exhibits a 61.09% degree of deacetylation determined via FTIR, with characteristic glycosidic linkage peaks. Then, it was applied to wine-making, and its impact on microbial diversity is evaluated by a next-generation sequencing method. Results show that this chitosan exerts a weaker antibacterial activity compared to SO 2 , but exhibits stronger antifungal efficacy, reducing fungal OTUs to 9 and eliminating all non- Saccharomyces yeasts. Moreover, the transcriptome profiling of S. cerevisiae in its presence reveals 177 differentially expressed genes. And gene expression levels associated with glycolysis and amino acid metabolisms are identified, with TDH2, TDH3, ENO1, ENO2, ARO10, ARO9, SER3 and GCV1 showing significant changes, resulting in accelerated utilization of sugar, enhanced aromatic amino acid catabolism, activation of proline production as well as suppressed serine synthesis pathways. Overall, this study provides novel insights into the application of chitosan in wine-making and its impact on microbial ecology and yeast metabolism.