Effects of nanobubble water supplementation on biomass accumulation during mycelium cultivation of Cordyceps militaris and the antioxidant activities of extracted polysaccharides

Abstract Cordyceps militaris (C.militaris) has traditionally been used as medicine and daily supplement for hundreds of years. Nanobubble water (NBW) can promote mass transfer, chemical reactions and metabolism. In this study, the NBW-liquid fermentation system was first established to evaluate the effects of NBW on mycelia of C. militaris. The highest mycelium concentration (3.90 mg/mL) and crude polysaccharides extraction yield (12.76%) were obtained in 25%-NBW group. The antioxidant activities of mycelia were significantly promoted after supplementation with NBW. The polysaccharides from 25%-NBW, 75%-NBW, and 50%-NBW groups exhibited the strongest DPPH radical, ABTS radical scavenging activities, and reducing power, respectively, achieving the highest radical scavenging rate (nearly 100% at 1.2 mg/mL), the lowest IC50 value (1.09 mg/mL) and the highest OD value (2.13 at 2.0 mg/mL). Results from this study suggest that NBW supplementation can be utilized as a new approach for bioactive compounds production from C. militaris.