Effects of Seasons and Daqu- making Process on the Microbial Community Structure and Metabolites of Bran Cuqu

In the present study, the effects of the seasons and technique on the microbial community and metabolites of traditional bran Cuqu were investigated by the Illumina MiSeq platform and chromatography technology, respectively. These results showed that both significantly impacted the community diversities and metabolic constituents. The abundances of the fungal and bacterial community in Cuqu manufactured in spring (L1) and summer (L2) were higher than those in the other two seasons, i.e., autumn (L3) and winter (L4). Besides, the fungal community structure of spring-Cuqu was similar to that of summer-Cuqu, so was the volatile profile displayed. Of them, Aspergillus in the L type of Cuqu was dominant and its abundance in L1 Cuqu was 70.74%. Moreover, the liquefying and saccharifying activity of L1 Cuqu were the highest among these samples. The liquefying activity, saccharifying activity, and total organic acid content of L1 Cuqu were significantly higher than those of Q Cuqu. Besides, there were significant differences in microbial community structures between them. The enzymes related to the biosynthesis of phenethyl alcohol in Q Cuqu showed a higher expression level than those in L1. The results of this study might provide a theoretical foundation for the optimization of the production process and scientific management of Cuqu.