Project description:The fermented and distilled Chinese alcoholic beverage strong flavor baijiu (SFB) gets its characteristic flavor during fermentation in cellars lined with pit mud. Microbes in the pit mud produce many key precursors of flavor esters. The over 20 year maturation time of natural pit mud have promoted attempts to produce artificial pit mud (APM) with shorter maturation time. However, knowledge on the molecular basis of APM microbial dynamics and associated functional variation during SFB brewing is limited, and the role of this variability in high quality SFB production remains poorly understood. We studied APM maturation in new cellars till the fourth brewing batch using 16S rRNA gene amplicon sequencing, real-time quantitative PCR and function prediction based on the sequencing results, and metaproteomics and metabolomics techniques. The results provide insight into global APM prokaryotic dynamics and their role in SFB production, which will be helpful for further optimization of APM culture technique and improvement of SFB quality.
Project description:Pit mud quality is a key parameter that impacts the quality of Chinese strong-flavor Baijiu production.This study was developed to explore spatial bacterial community distributions and the relationships between these distributions and the volatile compound accumulation within the pit mud used in the production of Chinese strong-flavor Baijiu. The results revealed Lactobacillus pasteurii and Limnochorda pilosa were found to be the dominant bacteria present in the upper wall, middle wall, and bottom pit mud layers, whereas the Clostridium genus was detectable at high levels in the lower layer of the pit wall and played a role in contributing to the overall aroma and flavor compounds in produced Chinese strong-flavor Baijiu, with Clostridium abundance being strongly correlated with caproic acid, ethyl caproate, ethyl butyrate, and hexanol levels as well as moderately correlated with butyric acid levels. The abundance of the Lactobacillus genus was positively correlated with levels of ethyl lactate, 1-butanol, and 2,3-butanediol. Limnochorda pilosa was closely associated with ethyl acetate levels. Additionally, the correlations between bacterial communities and chemical properties also investigated, and the results demonstrated PO43-, total carbon, K+, humus, NH4+-N, and Mg2+ levels significantly affected the bacterial community structure of pit mud, and they were positively correlated with the relative abundance of Clostridium. Together, these findings can serve as a foundation for future studies exploring the mechanisms whereby volatile compounds accumulate in different pit mud layers, which facilitates the fermentation regulation and pit mud quality improvement of Chinese strong-flavor Baijiu.
