Study On The Characteristics Of Mold Diversity In Maotai Town Sauce-flavor Liquor Brewing Area

The sauce-flavor liquor,one of the four major flavor liquors in China,has a long history of production.Unlike distilled spirits abroad,sauce-flavored liquor is brewed using traditional solid-state fermentation,the process is complex,and the wine has unique style characteristics such as outstanding sauce flavor,mellow wine,elegant and delicate,and long-lasting fragrance in empty glasses.Its open multi-bacterial mixed fermentation process determines that the formation of sauce-flavor liquor must be closely related to the succession of microbial community structure during fermentation.Among them,mildews can secrete amylase,protease,cellulase and other hydrolase systems,which have an important contribution to degrading brewing materials and promoting the formation of aroma and taste substances.Therefore,systematically exploring the characteristics of mildew diversity in the brewing area of Maotai Town sauce-flavor liquor will help to analyze the succession regular pattern of the mildew community during fermentation and the functional role of mold in the brewing process.In this study,high-throughput sequencing technology was used to systematically analyze the characteristics of the fungal flora diversity in Daqu and the brewing environment in the brewing area of Maotai Town’s main brewing area(tracking the entire sauce-flavor liquor brewing cycle).At the same time,mildews in the samples that can be cultured to isolate and identify were used to analyze the structure of the cultured flora.Finally,the solid state fermentation was simulated to investigate the metabolic enzyme activity structure,and the relative abundance and comprehensive enzyme activity characteristics of each mildew strain were used as two-way evaluation indicators to explore the dominant mildews that played the main function in the brewing process of Maotai Town sauce-flavor liquor.The research results are as follows:(1)Based on the Miseq platform,high-throughput sequencing technology was used to analyze the mildews of Daqu and environmental samples for brewing in 7main brewing areas of Maotai Town Sause-flavor Liquor.A total of 95 genera were detected,including 68 genera from Daqu samples and 89 genera from environmental samples.It is clear that Aspergillus,Byssochlamys,Monascus,Thermoascus,Thermomyces,Rhizomucor and other mildews were the dominant mildews in Daqu for brewing.Alternaria,Aspergillus,Byssochlamys,Cladosporium,Fusicolla,Lecythophora,Monascus Penicillium,Phoma,Pyrenochaeta,Thermoascus,Thermomyces,Toxicocladosporium and other mildews were the dominant molds in the brewing environment.The deep analysis of the degree of mutual migration of brewing Daqu in different main brewing areas and mildews in the surrounding environment provides a theoretical basis for the selection of wineries from the perspective of microorganisms.(2)Using traditional cultivable and 18 S r RNA gene sequencing technology to analyze Daqu and environmental sample mildews in 7 main brewing areas of Maotai Town Sause-flavor Liquor,which totaly identified 31 different mold species in 15 genera.It had been clarified that molds such as Lichtheimia,Mucor,Aspergillus,Monascus,Rhizomucor,Paecilomyces,Schizophyllum were the dominant mildews in the brewing environment,and Lichtheimia,Aspergillus,Penicillium,Phanerochaete,Thermoascus and other genera were the dominant mildews in Daqu.Deeply analysis of the brewing environment and the importance of mildew in Daqu on the fermentation of sauce-flavor liquor,from the microbiological point of view,the high-temperature Daqu and accumulation fermentation are the both inseparable brewing processes in sauce-flavor liquor.(3)Enzyme activity using bran to simulate solid state fermentation(amylase,acid protease and cellulase),the results of optimal enzyme production conditions showed that the optimum moisture content for mildew growth was 45% ～ 55%,the optimum p H value was 4.0 ～ 5.0,and the optimum fermentation temperature was30℃ ～ 35℃.Taking the enzymatic properties and relative abundance of mildews as research targets,59 types of molds isolated and identified were evaluated as 9 types.Itis classified that Lichtheimia corymbifera,Lichtheimia ramosa,Aspergillus tamarii,Aspergillus flavus,Aspergillus fumigatus,Aspergillus oryzae,Aspergillus terreus,Aspergillus clavatus,Monascus sp.Atc8,Monascus pilosus,Penicillium griseofulv Mycobacterial species with high enzyme activity and relatively high abundance,it is recommended to use these mildews as important microbiological indicators for brewing environment evaluation,monitoring,storage period of Daqu products and their quality evaluation.