Research On The Micro-ecological Diversity Of Jiangxiang Daqu Koji-making Based On High-throughput Sequencing

Maotai-flavor liquor is one of the oldest traditional liquor in China.Its brewing process is extremely complex and can be summarized as follows: high-temperature Daqu making,high-temperature accumulation,high-temperature fermentation,high temperature liquor distillation,long-term storage of base liquor.And high-temperature Daqu-making is a crucial link in the process of Maotai-flavor liquor-making,including four key phases: left the bricks in a room,the first overturning,the second overturning,and move brick out of the room.The significant difference between Maotai-flavor high temperature Daqu and Daqu of other flavor types is not only the high temperature of the Daqu,but also the complexity and succession complexity of the microbial flora in the Daqu-making process,the complexity of the enzymes in the Daqu,and the complexity of the sauce flavor of the Daqu.The characteristics of Daqu-making and Daqu blocks determine the yield and quality of Maotai-flavor liquor.Its core and key regulatory factors are the microbial flora structure and its changes during Daqu-making process.Therefore,it is of profound scientific and practical significance to investigate the structure of microbial flora and its changes in Daqu-making process.This study systemically researched microbial flora diversity and changes of its important microorganism of key phases(left the bricks in a room,the first overturning,the second overturning,move brick out of the room)in the traditional and mechanical Daqu-making of Guizhou XJ Company using high-throughput sequencing and its associated method,and the common and key microflora were analyzed.The differences between microbial diversity structure and important microbial species of Daqu in traditional and mechanical Daqu-making were compared and analyzed.The main research results obtained are as follows:(1)Results showed that 9 phyla and 90 genera bacteria were detected,of which the dominant phylums were Firmicutes,Proteobacteria and Actinobacteria,with Firmicutes being the most dominant phyla,while the major genus were Lentibacillus,Bacillus,Rhizobium,Kroppenstedtia and Thermoactinomyces.The heatmap,multi-species differences and other results also indicated that the structure of bacterial diversity between traditional and mechanical Daqu-making had no significant difference(including structure and abundance of genera).RDA analysis and correlation heatmap analysis revealed that Moisture of room,Humidity of room,Temperature of Daqu(QT)and Acidity of Daqu played a important role in regulating bacterial diversity structure,especially Humidity and QT.(2)4 phyla and 58 genera were detected from the traditional and mechanical Daqu.The bar of the community analysis showed that the predominant phylum were Ascmycota and Unclassfied Fungi,with Ascmycota being the most dominant phyla,and the major genus were Thermosacus,Thermomyces and Byssochlamys.Heatmap and other results indicated that there was no obvious difference in the fungal structure of the major microorganism during traditional and mechanical Daqu-making.RDA analysis and correlation heatmap analysis showed that Moisture,Humidity,QT,Acidity had obvious regulation on the fungal community structure,especially Humidity and QT.(3)A total of 28 predominant functional bacterial species were detected in the process of traditional and mechanical Daqu-making,mainly Bacillus and thermophilic bacteria.It is speculated that Bacillus,Lactobacillus,and Saccharopolyspora were functional microorganisms during the first overturning,while Lentibacillus and Oceanobacilus were functional microorganisms in the second overturning of the Maotai-flavored high temperature Daqu-making process.And there were 8 main functional fungal genera commonly owned,mainly thermophilic fungi.It was speculated that Themomyces was a functional fungal microorganisms during the first overturning,and Aspergillus and Byssochlamys were functional fungal microorganisms during the second overturning of Daqu-making process.(4)The microbial flora diversity of bacteria and fungi and the abundance of major bacteria in Daqu-making process showed that there had no obvious difference between the traditional and mechanical Daqu-making at the microbiological level,indicating that mechanical Daqu-making of Maotai-flavor Daqu was feasible.The mechanical Daqu-making of Maotai-flavor high temperature Daqu is conducive to the scientific and modern development of the traditional brewing.