Unravelling Metabolic Heterogeneity of Chinese Baijiu Fermentation in Age-Gradient Vessels.

Fermentation vessels affect the characteristics of food fermentation; however, we lack an approach to identify the biomarkers indicating fermentation. In this study, we applied metabolomics and high-throughput sequencing analysis to reveal the dynamic of metabolites and microbial communities in age-gradient fermentation vessels for baijiu production. Furthermore, we identified 64 metabolites during fermentation, and 19 metabolites significantly varied among the three vessels (p < 0.05). Moreover, the formation of these 19 metabolites were positively correlated with the core microbiota (including Aspergillus, Saccharomyces, Lactobacillus, and Bacillus). In addition, ethyl lactate or ethyl acetate were identified as the biomarkers for indicating the metabolism among age-gradient fermentation vessels by BP-ANN (R2 > 0.40). Therefore, this study combined the biological analysis and predictive model to identify the biomarkers indicating metabolism in different fermentation vessels, and it also provides a potential approach to assess the profiling of food fermentations.

Volatile organic compounds mediated endogenous microbial interactions in Chinese baijiu fermentation.

Microorganisms release abundant volatile organic compounds, and these compounds have important roles in distant interactions and communication. However, the effects of microbial volatile organic compounds on microbial interactions remains unclear in traditional food fermentations. In this study, we applied high-throughput sequencing analysis to reveal the structure and succession of microbial community in the preparations of Qu starter for Chinese baijiu fermentation. The genus Weissella, Pediococcus, Lactobacillus, Saccharomycopsis, Saccharomyces, Candida and Rhizopus were dominant and varied in this preparation, and the abundant Rhizopus had a positive correlation with Lactobacillus in situ system. In addition, benzyl alcohol produced by Rhizopus microsporus could significantly promote the growth of Lactobacillus fermentum in a simulative baijiu fermentation under laboratory. Moreover, the addition of benzyl alcohol could enhance the activation of alanine, aspartate and glutamate metabolism and arginine biosynthesis for promoting the growth of Lactobacillus fermentum through transcriptional analysis. Therefore, this study revealed volatile organic compounds from microorganisms could meditate the endogenous microbial interactions in Chinese baijiu fermentation. Furthermore, it provides a potential approach to add or remove volatile organic compounds to regulate the microbial interactions, for improving traditional food fermentations.