Abstract: Metabolomics was used to analyze the changes in metabolites （X51, X55） and key metabolic pathways in fennel before and after fermentation with Cordyceps spp. strains 51 and 55. The results showed that fermentation altered the metabolic profile of fennel compared to the control group (XK). The patterns of differential metabolite changes were similar between XK vs X51 and XK vs X55 comparisons, with 310 and 297 upregulated metabolites, respectively, primarily amino acids and their derivatives, and 423 and 400 downregulated metabolites, respectively, primarily phenolic acids. In both the XK vs X51 and XK vs X55 comparisons, the main upregulated metabolites included L-ornithine and cyclo(L-leucine-trans-4-hydroxy-L-proline), among others. The upregulation of these metabolites might be closely related to the pharmacologically active components of fennel. The differential metabolites from XK vs X51 and XK vs X55 comparisons were mainly enriched in biosynthesis of secondary metabolites, biosynthesis of cofactors, and biosynthesis of amino acids. The annotation proportion of the biosynthesis of secondary metabolites pathways all exceeded 39%, indicating that this pathway might play a core regulatory role during the fermentation process.

Key words: fungal fermentation, Cordyceps spp., fermentation, fennel, metabolites