Elucidating microorganism–metabolite interactions during Xinyang black tea fermentation through integrated widely targeted metabolomics and high-throughput sequencing

Background Fermentation is an indispensable step in the processing of Xinyang black tea (XYBT). This study aimed to unveiling the correlation between microorganisms and metabolites in the fermentation process of XYBT by widely targeted metabolomics and high-throughput sequencing techniques. Results Widely targeted metabolomics detected 682 metabolites in XYBT during fermentation. Among these, 45 differentially metabolites were screened through orthogonal partial least-squares discrimination analysis (OPLS-DA) during XYBT fermentation (VIP > 1 and p  < 0.01). Concurrently, high-throughput sequencing revealed dynamic shifts in both bacterial and fungal community composition over the course of XYBT fermentation. At the genus level, Sphingomonas , Chryseobacterium , Herbaspirillum , Aureimonas , Agrobacterium , and Microbacterium constituted the predominant bacterial genera in XYBT during fermentation, while Cladosporium , Setophoma , Alternaria , Wallemia , Aspergillus , Neodeviesia , and Fusarium represented the major fungal genera. Spearman’s correlation analysis further demonstrated that metabolite abundances were significantly linked to 5 bacterial and 10 fungal genera at the p  < 0.05 threshold. Notably, Chryseobacterium displayed positive associations with quercetin-1, 1-monomyristin, and brevifolincarboxylic acid. Setophoma and Plectosphaerella were positively linked to quercetin-1, 1-monomyristin, and D-leucine, whereas rutin and ferulic acid exhibited inverse relationships with these genera. Conclusion These findings offer novel insights into the microbial diversity and their role in regulating the metabolites of XYBT during fermentation.