Mechanism of the secondary metabolites and key enzymes of Monascus spp. to promote tocopherol enrichment

Monascus-fermented coix seed exhibits enhanced tocopherol accumulation compared to other strains, yet mechanisms remain unclear. Whether Monascus metabolites/enzymes drive this enrichment is worth exploring. Comparative genomics and transcriptomics were employed to analyze secondary metabolite profiles and tocopherol enrichment capabilities across Monascus strains. The results revealed that γ-aminobutyric acid (GABA) derived from amino acid metabolism is channeled into both the Shikimate pathway to generate homogentisic acid (a tocopherol precursor) and the Mevalonate pathway to produce ergosterol and geranylgeranyl diphosphate (another precursor). Furthermore, the total tocopherol content of M1 and M1 + 3 reached 168 and 148 μg/g DW, positively correlating with ergosterol content (p < 0.05). Transcriptomic data further demonstrated strain-specific differences in tocopherol enrichment, linked to upregulated expression of key genes (HPPD, ERG4, MVD, FDPS, GGPS1) governing precursor biosynthesis. Crucially, we validated that ergosterol acts as a stimulator of tocopherol synthesis, directly supporting our hypothesis on pathway crosstalk. This study elucidates microbial-driven tocopherol enrichment mechanisms via precursor allocation and transcriptional regulation, providing insights into bioactive compound synthesis in complex metabolic networks.