中高温大曲在制曲过程中微生物区系演替特征及功能研究

Succession of microbial communities and function of medium-hightemperature Daqu during the starter-making process

作为白酒酿造的发酵剂,大曲对白酒质量有重大影响。为解析中高温大曲的微生物菌群结构演替规律和理化特征变化,该研究通过Illumina NovaSeq二代测序技术分析浓香型白酒中高温大曲制作过程中细菌和真菌菌群结构特征;并结合大曲的含水量、还原糖和液化力等理化与生化性质,分析微生物菌群与大曲功能的相关性。结果表明,大曲中的真菌归属于8个门、255个属,细菌归属于10个门、262个属;其中,优势真菌属为Issatchenkia、Thermoascus、Trichocladium、Aspergillus、Rhizopus和Rhizomucor,优势细菌属为Weissella和Lactobacillus。相关性分析显示,温度是影响大曲微生物结构的主要环境因子,Rhizopus、Rhizomucor、Weissella和Lactobacillus是影响大曲功能的主要微生物。在制曲过程中,大曲液化力和糖化力于28 d分别达到最大值(0.27 U和582.00 U),酯化力于13 d达465.54 U,发酵力于7 d达1.6 U。通过二代测序技术分析发现微生物的菌群结构在中高温大曲制作过程存在动态变化,从而改变酒曲功能性质。

Daqu is a fermentation starter commonly used in the Chinese Baijiu-making process and it prominently influences the qual-ity of Chinese Baijiu.To reveal the succession of microbial community structure and physicochemical changes of medium-high-temperature Daqu during the starter-making process,second-generation sequencing technology(Illumina NovaSeq 6000)was used to analyze the bac-terial and fungal communities involved in the starter-making process of Daqu for strong-flavor Baijiu.The physical,chemical,and bio-chemical properties of Daqu,such as water content,reducing sugar content,and liquefaction power,were measured to analyze the rela-tionship of microbial communities and Daqu function.The results showed that the fungi in Daqu mainly belonged to 8 phyla and 255 gene-ra,while the bacteria were classified to 10 phyla and 262 genera.The major fungal genera were Issatchenkia(28.12%of total se-quences),Thermoascus(16.16%),Trichocladium(14.14%),Rhizopus(7.15%),Aspergillus(6.44%),and Rhizomucor(5.43%);the dominant bacterial genera were Weissella(39.60%)and Lactobacillus(17.43%).Correlation analysis revealed that tem-perature was the primary environmental factor influencing the microbial community structure in Daqu.Rhizopus,Rhizomucor,Weissella,and Lactobacillus were identified as the major microbial taxa contributing to the function of Daqu.During the starter-making process,the liquefaction power and saccharification power of Daqu reached their maximum levels of 0.27 U and 582.00 U at 28 d,respectively;the es-terification power reached a peak value of 465.54 U at 13 d;and the fermentation power reached up to 1.6 U at 7 d.This study indicated that the microbial community structure evolved dynamically in medium-high-temperature Daqu during the starter-making process,thereby altering the functional properties of the starter for Chinese Baijiu.