Microbiome-metabolome correlations across vertical stratification in Jiupei of strong-flavored baijiu fermentation

The differences in the microbiota and metabolites from the different vertical stratification in Jiupei are obvious but not entirely clear. This study used high-throughput sequencing and metabolomics techniques to explore the microbiome and metabolites of varying vertical stratification in Jiupei and their relationships. The results showed that most beneficial metabolites, including pentadecanoic acid, ricinoleic acid, and epigallocatechin, were significantly higher in the lower Jiupei layer. Some volatile compounds gradually showed upregulation with increased Jiupei depth, mainly esters, ketones, and terpenoids. The bacterial community diversity of Jiupei decreased significantly with the increase in depth, Acetilactobacillus jinshanensis dominated the Jiupei bacterial community, and its relative abundance increased significantly (P < 0.05) with the rise of Jiupei depth (P < 0.05). The fungi Aspergillus oryzae (P = 0.057) and Byssochlamys spectabilis increased significantly, Dipodascus australiensis (P < 0.05), Pichia kudriavzevii (P = 0.08), and Dipodascus geotrichum (P < 0.05) gradually decreased. The correlation relationship analysis revealed that the dominant microbes that caused the metabolites and volatile compounds differences were the bacterium Acetilactobacillus jinshanensis and the fungus Aspergillus oryzae as well as Byssochlamys spectabilis, which may be through biosynthesis of other secondary metabolites and lipid metabolism to impact the Jiupei metabolites. The study demonstrated the microbiome and metabolite differences in three layers of Jiupei and the effect of microbes on the characteristic metabolite formation of strong-flavor baijiu.