Title : Dual fermentation of cereals: Boosting bioactivity with hericium erinaceus and probiotics
Abstract:
Hericium erinaceus is a medicinal mushroom with neuroprotective and antioxidant properties, whose bioactive compounds are being studied for applications in functional foods and nutraceuticals. Cereal substrates provide a suitable medium for its cultivation, as they are rich in complex carbohydrates, fiber, and essential nutrients that support fungal growth and the production of secondary metabolites. At the same time, cereals are nutritionally valuable and easily digestible, making them an ideal base for the development of functional foods enriched with bioactive compounds formed during the fermentation process. This study investigates the effects of cultivating the medicinal mushroom Hericium erinaceus on the nutritional and biological properties of various cereal substrates, followed by lactic acid fermentation using the probiotic bacterium Lactobacillus rhamnosus. The two-step biotechnological approach involved fungal mycelium growth on gluten-free or partially gluten-free substrates, followed by probiotic fermentation aimed at enhancing the bioavailability and bioactivity of naturally occurring compounds. The cultivation of H. erinaceus resulted in a significant increase in the levels of free phenolic compounds, flavonoids, tocopherols, and ergosterol. Antioxidant activity as well as the content of water-soluble proteins and lipids, was also markedly enhanced. This enhancement is attributed to the enzymatic activity of the fungus, which may release bound phenolics from fiber or protein matrices within the substrate. After fermentation with L. rhamnosus, samples were analyzed for lactic acid content, antioxidant activity, and antimicrobial potential. Fermentation led to a moderate but statistically significant increase in antioxidant capacity and bioactive compound concentration. Antimicrobial activity was evaluated against Escherichia coli and Micrococcus luteus. The strongest inhibitory effects were observed in fermented extracts where both fungal and probiotic activities were combined. Cytotoxicity was evaluated using the MTT assay on human Caco-2 cells, showing no toxic effects. In conclusion, the combination of Hericium erinaceus cultivation and probiotic fermentation significantly enhances the nutritional and biological quality of cereal substrates. These results support the potential application of fermented fungal–cereal matrices as functional food components or dietary supplements with synergistic antioxidant and antimicrobial properties.
