Solid-State Fermentation of Riceberry Rice with Mushroom Mycelium for Enhanced Beta-Glucan Production and Health Applications

Beta-glucans (β-glucans), polysaccharides found in cereals and fungi, are recognized for their prebiotic and potential anti-cancer activities, particularly in the colorectal area. This study aims to optimize the production of β-glucan through the solid-state fermentation of germinated Riceberry rice with <i>Pleurotus ostreatus</i> and evaluate the bioactivities of the resulting extract. The crude β-glucan extract, obtained with a recovery rate of 54.95% and 79.98% purity, demonstrated an effective extraction process, as confirmed by thermogravimetric analysis (TGA). Fourier-transform infrared spectroscopy (FTIR) analysis verified the presence of β-1,3/1,6-glycosidic linkages, characteristic of the bioactive β-glucans found in yeast and mushrooms. The biological assessment demonstrated the extract's functional properties. At a concentration of 1 mg/mL, the crude β-glucan extract significantly promoted the growth of probiotics <i>Lacticaseibacillus rhamnosus</i> and <i>Bacillus coagulans</i>, exhibiting high Prebiotic Index (PI) values of 6.36 ± 0.72 and 115.70 ± 10.19, respectively, with PI values indicating strong prebiotic potential. For comparison, the standard prebiotic inulin yielded PI values of 0.41 ± 0.09 and 90.53 ± 2.28 for the same respective bacteria, highlighting the superior performance of the fungal-fermented β-glucan. Furthermore, the extract displayed efficacy in inhibiting colon cancer cells in preliminary in vitro tests. It reduced the viability of the SW480 colorectal cancer cell line by 66.23% and induced cell death in 27.94 ± 0.93% of the cells after 48 h of treatment, performing comparably to a commercial yeast β-glucan standard. Crucially, the extract showed no significant cytotoxicity toward the normal human colon cell line, CCD-841 CoN. These findings highlight the promising method of fungal solid-state fermentation on germinated Riceberry rice in the production of high-purity, bioactive β-glucans for use in functional foods.