Strategies for enhancing tocopherol enrichment based on strain screening, optimization, and regulation

Tocopherol is a widely used nutritional supplement and antioxidant, but its low yield limits applications. Regulation of microbial fermentation is an effective strategy to achieve high-level enrichment of target metabolites. In this study, Monascus. rubiginosus ( M. rbg ) exhibited the greatest total tocopherol accumulation ability among the four Monascus spp. during coix seed fermentation, reaching 22.85 μg/g, particularly enriching γ-tocopherol (14.36 μg/g). After UV mutagenesis (30 W, 25 cm, 120 s), total tocopherol enrichment in the optimization strain ( M.rbg -2 M) increased to 68.09 μg/g (2.98-fold). Regulation of key factors further enhanced tocopherol enrichment. The addition of L -phenylalanine (L-Phe, 15 mM), L-tyrosine (L-Tyr, 5 mM), and sodium dodecyl sulfate (SDS, 0.4%) increased total tocopherol to 137.89, 130.03, and 106.62 μg/g, respectively, and promoted β-tocopherol enrichment. Box–Behnken design analysis identified the optimal interaction of L-Phe (10 mM), L-Tyr (10 mM), and SDS (0.4%), which elevated total tocopherol in the M. rbg -2 M to 346.49 μg/g, over fifteen-fold higher than the initial strain ( M.rbg , 22.85 μg/g), and promoted δ-tocopherol enrichment. This study demonstrates that integrating strain improvement with fermentation regulation strategies effectively enhances tocopherol enrichment and isomer-specific enrichment., providing insights for microbial accumulation of bioactive compounds in cereal-based fermentation.