Key Laboratory of Industrial Biotechnology of Ministry of Education, State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China. [Email] [Email]
Chinese Jiuqu (starter) provides saccharifying enzymes for baijiu (Chinese liquor) fermentation, which undergoes a simultaneous saccharification and fermentation process. However, the key saccharifying enzymes associated with alcoholic fermentation from Jiuqu and their effects on ethanol production remains poorly understood. In this study, we identified 51 carbohydrate hydrolyses in the baijiu fermentation by metaproteomics analysis. Through source tracking analysis, approximately 80% of carbohydrate hydrolyses in the baijiu fermentation were provided by Jiuqu Among these enzymes, alpha-amylase (EC 126.96.36.199) and glucoamylase (EC 188.8.131.52), from Aspergillus, Rhizomucor and Rhizopus, were positively related to starch hydrolysis and ethanol production, indicating that they were the key saccharifying enzymes associated with alcoholic fermentation in the baijiu fermentation. Moreover, a combined mixture of alpha-amylase and glucoamylase (in a ratio of 1:6, w/w) enhanced ethanol production in a simulative baijiu fermentation under laboratory. This result revealed a synergistic effect of multi-saccharifying enzymes on ethanol production in baijiu fermentation. Our study provides a potential approach to improve the efficiency of saccharification and alcoholic fermentation by optimizing the profile of saccharifying enzymes for baijiu and other beverages fermentation.IMPORTANCEJiuqu starter provides enzymes to the simultaneous saccharification and fermentation process of baijiu production, however, the key saccharifying enzymes associated with alcoholic fermentation from Jiuqu and their effects on ethanol production remains unclear. We confirmed Jiuqu was the main source of carbohydrate hydrolyses for baijiu fermentation, and identified two type saccharifying enzymes from multi-microbes as the key enzymes associated with alcoholic fermentation. Moreover, a proper combination of multi-saccharifying enzymes could enhance ethanol production in baijiu (Chinese liquor) fermentation. This combination provides an approach to optimize the profile of saccharifying enzymes for enhancing ethanol production in baijiu and other food fermentations.