Analysis of microbial diversity and physicochemical property of high-temperature Daqu in Changde area

Using 6 high-temperature Daqu samples collected from a distillery in Changde City, Hunan Province as the research objects, the microbial diversity of the samples was analyzed using Illumina MiSeq high-throughput sequencing and pure culture technology, and their physicochemical indicators were further measured to explore the correlation between physicochemical indicators and dominant microorganism genera. The results showed that the richness and diversity of bacterial communities in 6 high-temperature Daqu were significantly higher than those of fungal communities (P<0.01). The dominant bacterial genera in Daqu were Lentibacillus, Kroppenstedtia, Saccharomyces, Thermoactinomyces, Bacillus, Staphylococcus, Weissella and Companilactobacillus, with the average relative abundance of 20.60%, 19.51%, 17.93%, 11.53%, 8.90%, 4.92%, 3.32% and 1.27%, respectively. The dominant fungal genera were Thermomyces, Aspergillus, Saccharomyces, Dipodascus, Byssochlamys, Rhizopus, Thermomucor and Thermoascus, with the average relative abundance of 60.88%, 11.64%, 7.86%, 4.67%, 2.23%, 2.11%, 1.27% and 1.24%, respectively. The cultivable microorganisms isolated and identified from the samples were Bacillus licheniformis and Saccharomycopsis fibuligera. Lentibacillus was highly significantly negatively correlated with ash content (P<0.001), Bacillus was significantly negatively correlated with alcohol and saccharification power, and Thermomyces was significantly negatively correlated with moisture and amino acid nitrogen (P<0.05).