Exploration and application of Saccharomyces cerevisiae NJ002 to improve the fermentative capacity of medium-high temperature Daqu

Abstract

Daqu is crucial for brewing Chinese Baijiu. The application of yeast with high fermentative capacity and adaptive ability to produce fortified Daqu could be a viable strategy for improving its fermentative capacity. In this study, Saccharomyces cerevisiae NJ002, the first report about S. cerevisiae with high fermentative capacity and highlighted tolerance to temperature (60 °C), acid (pH 2) and ethanol (12 % v/v), was isolated from Daqu. Three factors, including the contents of glucose, nitrogen sources, and ethanol, were chosen to optimize NJ002 growth using the Box-Behnken design-response surface methodology. The OD600 of optimized NJ002 was 47.42 % higher than that before optimization. When 4-litre optimized NJ002 was added to produce one-room fortified Daqu, the fermentative capacity (fermentation for 18 days) increased by 116.67 % compared to that of normal Daqu. This study can be used for improving the fermentative capacity of Daqu and is valuable for reducing consumption of grains and energy.