Analysis of the Structure and Function of High Temperature and Rapid Fermentation Douchi Flora Based on Macrogenome Sequencing Technology

To reveal the change rule of the microbiota structure of high-temperature fast-fermented Aspergillus-type Douchi during the fermentation process, and to analyze the difference between the distribution of functional gene and its contribution in different fermentation stages. The diversity of the microbiota and its function in high-temperature fast-fermentation Douchi was analyzed based on metagenomics methods, so as to reveal the changes in the microbiota structure and the distribution of metabolic functions. The results of microbiota structure diversity showed that the bacteria occupied the 98.9%~99.8% of organisms in fermented Douchi. In the early stage of fermentation, the four dominant genera Weissella, Lactobacillus, Pediococcus and Enterococcus were all lactic acid bacteria, which accounting for 69.91% of the microbiota. In the middle and late stages, obligate anaerobic bacteria such as Bacteroide, Prevotella, and Enterococcus were dominant genera. The KEGG results showed that genes related to metabolism accounted for more than 50%, indicating that the fermentation process was vigorous in metabolism, of which carbohydrate metabolism and amino acid metabolism were the main metabolic pathways. The CAZy results showed that the gene abundance of glycoside hydrolase and glycosyltransferase was the highest, indicating that the glycoside transfer was active during the fermentation process, where the abundant oligosaccharides and monosaccharides were produced for the metabolic utilization of microbial community. The above research can provide a new insight for the improvement of the multi-bacteria mixed fermentation process of Douchi, and also lay a foundation for the subsequent application of multi-omics technology to explore the internal mechanism of the formation of microorganisms and functional flavor substances in Douchi.