Genome-Edited Nuruk-Derived Yeast for Enhancing Quality and Flavor of Fermented Foods

While esters are known to provide fruity and floral characteristics, their production is often insufficient to meet consumer preferences. In this study, Saccharomyces cerevisiae N9 isolated from Korean nuruk (fermentation starter) was engineered using Cas9-based genome editing and applied to the production of Korean rice wine (makgeolli). URE2, coding for a transcriptional regulator of nitrogen catabolite repression, was deleted to increase the secretion of savory amino acids. ATF1, coding for alcohol acetyltransferase 1, was overexpressed to intensify the production of ester-based flavor compounds, whereas IAH1, coding for esterase, was deleted to increase ester accumulation. Ester intensity was further modulated in YPD medium by controlling ATF1 expression and mixed-culture ratios, while Makgeolli made with the URE2-deleted or ATF1/IAH1-engineered strains showed increased amino acid or ester levels. As no foreign DNA was introduced, these strains may not be subject to GM regulation in the United States, supporting their broader application in fermented foods.