Analysis of microbiome succession and metabolome dynamics in Jiupei during Chinese strong-flavor Baijiu fermentation

Microbial successions during Jiupei fermentation are critical for the flavor synthesis of strong-flavor Baijiu, but their dynamics and associated metabolites across different vertical Jiupei layers have not yet been characterized in detail. This study employed metagenomic sequencing combined with metabolomic techniques to investigate the complex relationship between microbial succession and metabolite formation in Jiupei of strong-favor Baijiu fermentation. Results demonstrated that a total of 2940 compounds were identified and classified into 13 classes; of which over 94.7% of amino acids and derivatives, 57.5% of organic acids, and certain sugar alcohols increased during fermentation, whereas more than 81.8% of flavonoids decreased, particularly in the lower Jiupei layer. The volatile compounds, including ethyl caproate and ethyl lactate, showed a significant increase. Meanwhile, microbial diversity and richness dropped sharply from day 0 to day 30, with a recovery by day 60 in the middle and lower layers. The early stage of fermentation is characterized by the fungi Paecilomyces variotii, Lichtheimia ramosa, Rhizopus arrhizus, and Aspergillus chevalieri, as well as the bacteria Saccharopolyspora rectivirgula, Lactiplantibacillus plantarum, Leuconostoc citreum, and Weissella confusa, which secrete amylases and glycosylases to hydrolyze starch into sugars via enrichment of carbohydrate-related pathways, such as starch and sucrose metabolism, glycolysis/gluconeogenesis, and fructose and mannose metabolism. Acetilactobacillus jinshanensis, Lentilactobacillus diolivorans, and Philodulcilactobacillus myokoensis sharply increased in the later stage of fermentation, alongside enriched pathways for fatty acid and secondary metabolite biosynthesis. Acetilactobacillus jinshanensis ‌might synergistically accumulate characteristic flavor compounds through transferase and ligase reactions. These findings reveal the stage-specific microbial metabolic characteristics and synergistic mechanisms in flavor formation, providing a scientific basis for optimizing Baijiu fermentation processes to enhance Baijiu quality.