Multiple sugars promote microbial interactions in Chinese baijiu fermentation

The utilization of fermentable sugars determines the succession and metabolism of microbial communities in traditional food fermentations. However, the profile of fermentable sugars and their effects on the microbial interactions and metabolism remains poorly understood. In this study, we revealed the compositions of fermentable sugars in the baijiu fermentation, including maltose, cellobiose, glucose, d-galactose and arabinose. Furthermore, we found the specific sugars (glucose and maltose) were positively correlated with the growth of the abundant genera Lactobacillus and Saccharomyces in the baijiu fermentation. Moreover, a proper combination of sugars mixture (glucose and maltose in a ratio of 9:1, wt/wt) enhanced the symplastic growth and interactions of Lactobacillus and Saccharomyces strains in a simulative baijiu fermentation under the laboratory. Meanwhile, the biomass of Lactobacillus and Saccharomyces strains in the cultivation by the optimized sugars combination were 1.21- and 1.19-fold higher than that of cultivation by the single substrate-sugar. In addition, the formation of these sugars were associated with the saccharifying enzymes from Jiuqu, like GH13 (alpha-amylase, EC 3.2.1.1), GH15 (glucoamylase, EC 3.2.1.3) and so on. This study indicated that specific sugars in substrate-sugars promoted the microbial interactions in baijiu fermentation.