Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, PR China; Department of Brewing Engineering, Moutai Institute, Renhuai 564507, PR China.
National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, PR China; Jiangsu Provincial Engineering Research Center for Bioactive Product Processing, Jiangnan University, Wuxi 214122, PR China.
Food Res Int. 2022 Jun;156:111298. doi: 10.1016/j.foodres.2022.111298. Epub 2022 Apr 26.
High-temperature Daqu, usually used as a fermentation starter for sauce-flavor Baijiu production, plays an essential role in the yield and flavor quality of Baijiu. The environmental heterogeneity of different locations in the workshop during fermentation led to the final production of Daqu with three different types (i.e., white, yellow, and black Daqu). How to use these three types of Daqu in Baijiu production mainly depends on the workers' experience so far. Here, we aimed to reveal the potential functions of different types of Daqu by comparing enzyme activity, volatile metabolites, and microbiota characteristics. White_Qu exhibited the highest liquefaction and saccharification enzyme activities, while the highest neutral proteinase and cellulase enzyme activities were detected in black_Qu. The total volatile content of yellow_Qu and black_Qu was roughly double that of white_Qu, and multivariate analysis revealed distinct volatile dissimilarities across different types of Daqu. Significant differences in bacterial and fungal community structures, assembly patterns, and potential functional profiles were discovered among different types of Daqu. At the genus level, Oceanobacillus and Thermomyces dominated the white_Qu microbiota, and the abundant microbes in yellow_Qu and black_Qu were scattered in Kroppenstedtia and Thermoascus. Bacterial and fungal communities were dominated by deterministic and stochastic assembly processes, respectively, suggesting that bacteria may be more affected by abiotic environmental factors and species interaction than fungi. Co-occurrence network analysis showed positive correlations characterized Daqu microbial networks, and network topological features indicated stronger interactions between bacterial taxa compared with fungal community. The Spearman correlation analysis revealed that four bacterial genera (Kroppenstedtia, Virgibacillus, Scopulibacillus, and Staphylococcus) and two fungal genera (Thermoascus and Aspergillus) exhibited positive correlations with almost all of the abundant volatiles. This work reveals that spatially varying environments lead to the microbiome and metabolome heterogeneity of high-temperature Daqu in the same workshop.
高温大曲，通常用作酱香型白酒生产的发酵起始剂，在白酒的产量和风味质量方面起着至关重要的作用。发酵过程中车间不同位置的环境异质性导致最终生产出三种不同类型的大曲（即白曲、黄曲和黑曲）。如何在白酒生产中使用这三种类型的大曲主要取决于工人迄今为止的经验。在这里，我们旨在通过比较酶活性、挥发性代谢物和微生物区系特征来揭示不同类型大曲的潜在功能。白曲表现出最高的液化和糖化酶活性，而黑曲则检测到最高的中性蛋白酶和纤维素酶活性。黄曲和黑曲的总挥发性含量大致是白曲的两倍，多元分析揭示了不同类型大曲之间明显的挥发性差异。不同类型的大曲在细菌和真菌群落结构、组装模式和潜在功能谱方面存在显著差异。在属水平上，海洋杆菌和嗜热丝孢菌主导了白曲的微生物群，而黄曲和黑曲中丰富的微生物则分散在克罗彭施泰特菌和嗜热曲霉属中。细菌和真菌群落分别以确定性和随机性组装过程为主导，这表明细菌可能比真菌更容易受到非生物环境因素和物种相互作用的影响。共现网络分析显示了阳性相关性，这些相关性特征化了大曲微生物网络，网络拓扑特征表明细菌类群之间的相互作用强于真菌群落。Spearman 相关性分析显示，四个细菌属（克罗彭施泰特菌、脆弱杆菌、鞘氨醇单胞菌和葡萄球菌）和两个真菌属（嗜热曲霉属和曲霉属）与几乎所有丰富的挥发性物质呈正相关。这项工作表明，空间变化的环境导致了同一车间高温大曲的微生物组和代谢组的异质性。
