Effects of Different Daqu on Microbial Community Domestication and Metabolites in Nongxiang Baijiu Brewing Microecosystem

Abstract

The quality and yield of the fresh Baijiu mainly depend on the activity of pit mud (PM) and the quality of Daqu. However, the cultivation of PM is a long-term process, and high-quality Daqu can change the community structure of fermented grain (FG) and accelerate the evolution of PM communities. The present research aimed to investigate the four different types of Daqu on the FG-fermenting microbial community structure and metabolites and their interphase interactions with PM. These results show that Kroppenstedtia in the bacterial community of Taikong Daqu (TK) was positively correlated with ethyl caproate, which significantly increased the content of FG volatile metabolites, especially lipid components, and facilitated the accelerated evolution of Methanobacteriales and Methanosarcinales in PM. Bacillus has a high relative abundance in Qianghua Daqu (QH), which shows obvious advantages to improving the alcoholic strength of FG and contributing to increasing the abundance of Methanomicrobiales in PM. Qianghua and traditional-mixed Daqu (HH) have a similar bacterial composition to QH and a similar fungal composition to traditional Daqu (DZ), and thus also showed the advantage of increased yield, but the volatile flavor metabolites produced were not as dominant as DZ. β-diversity analysis showed that in TK fermentation systems, FG is more likely to domesticate the structure of PM microorganisms. These results indicated that the interaction between microbial communities in Baijiu fermentation niches was significantly influenced by different Daqu. It can not only enhance the key volatiles in FG but also accelerate the evolving direction of the community in PM. Daqu fortified by functional genera or microbiota can evolve a community structure more suitable for Baijiu fermentation. The microbiota composition and interaction between the communities in both Daqu and PM significantly impacts the yield and quality of the base liquor.

Phenolic metabolites changes during baijiu fermentation through non-targeted metabonomic

“…6 c (E vs C) showed that a total of 19 different phenolic metabolites were identified in fermented grains before koji mixing and after the mixing of Daqu , of which 6 were up-regulated and 13 were down-regulated. It was possible that the mixing of Daqu down-regulated a large parts of phenolic metabolites, because Daqu was mainly a collection of beneficial microbial communities and contained a very small number of phenolic substances ( Mao, Huang, Zhou, et al, 2022 ). Fig.…”

Seasonal dynamics of the microbial community in a strong‐flavor baijiu fermentation

“…Many studies in the past decade have focused on microbial distributions and the factors influencing the micro-ecosystem of baijiu brewing. 3,8,[27][28][29][30] However, few of them have evaluated the impact of seasonal variations on microbial communities, physicochemical indices, and VFCs in the SFB fermentation system. 22 In this study, we investigated the diversity and assembly of microbes presented in the ZP used for SFB production across four seasons, as well as their correlations with environment variables.…”

“…For example, Bacillus and Acetobacter are positively correlated with forming acetate esters, while Lactobacillus is significantly associated with lactic acid 5 . Kroppenstedtia is positively correlated with ethyl caproate, 8 and Caproiciproducens , Syntrophaceticus , Sedimentibacter , Hydrogenispora , Pelotomaculum , and Bacillus notably affected the production of hexanoic acid 9 …”

Rapid detection of six Oceanobacillus species in Daqu starter using single‐cell Raman spectroscopy combined with machine learning

“…Since the fermentation process is carried out in an open environment, the structure of Daqu microbiota can be easily affected by raw materials (Zhang et al., 2022 ), environmental factors (e.g., tools, indoor ground, room temperature) (Li et al., 2016 ; Zhang et al., 2022 ) and fermentation technology (e.g., ventilation, packing method) (Kang et al., 2022 ), resulting in different Daqu types. Recent studies have revealed that fermenting Daqu with different raw materials leads to varying microbial characteristics (Mao et al., 2022 ). Daqu ‐making environments, such as indoor ground and tools, are the main sources of fungal communities in Daqu , while raw materials primarily contribute to bacterial communities (Du et al., 2019 ).…”