Analysis on the microbial community structure and differences in Daqu and fermented grains of strong-flavor and light-flavor Baijiu based on high-throughput sequencing

In order to investigate the microbial community structure in the Daqu and fermented grains at the later stages of fermentation for strong-flavor (Nongxiangxing) and light-flavor (Qingxiangxing) Baijiu, analyze the similarities and differences in microbial communities between the two types of Baijiu production, the microbial community structure in Daqu and fermented grains was analyzed by high-throughput sequencing technology. The results showed that the richness and diversity of bacteria were significantly higher than that of fungi in both flavor type of Daqu and fermented grains. There were two specific strains in strong-flavor Daqu. At the bacterial genus level, the relative abundance of Weissella in strong-flavor Daqu was much higher than that in light-flavor Daqu (23% and <1%, respectively), while the relative abundance of Pantoea was lower than that of light-flavor Daqu. The relative abundance of Acetobacter in the fermented grains of strong-flavor Baijiu was the highest, the relative abundance of Lactiplantibacillus in fermented grains of light-flavor Baijiu was the highest. At the fungal genus level, the relative abundance of Pichia and Saccharomyces in Daqu and fermented grains of strong-flavor Baijiu were the highest, respectively. The relative abundance of Saccharomycodes and Saccharomyces in Daqu and fermented grains of light-flavor Baijiu were the highest, respectively. The relative abundance of Pichia in strong-flavor Daqu (66%) was much higher than that in light-flavor Daqu (2%). The difference of community abundance in strong-flavor Daqu was larger, while the difference of community abundance in light-flavor Daqu was balanced. Saccharomyces was the most abundant genus in both flavor types of fermented grains. The relative abundance of Aspergillus in the fermented grains of strong-flavor Baijiu (6%) was lower than that in light-flavor Baijiu (18%), while the relative abundance of Naumovozyma (20%) was higher than that in light-flavor Baijiu (1%). These findings provided a theoretical basis for clarifying the formation mechanism of Baijiu flavor types and the cultivation and screening of functional microorganisms.