Study on selenium absorption ability of Ophiocordyceps sinensis fungus in liquid cultures

Abstract

Ophiocordyceps sinensis is a medicinal mushroom which is highly valued in traditional and modern medicine. Besides, selenium (Se) is an essential trace element in the human body. Therefore, the study on selenium accumulation ability of O. sinensis fungus to improve its bioactivities as well as selenium bioavailability is extremely imperative. In this research, O. sinensis cultured on liquid medium with sodium selenite (Se⁺⁴) or sodium selenate (Se⁺⁶) at 0–30 mg/L concentrations, then isolated three selenium-containing compounds including selenium-exopolysaccharide (Se-EPS), selenium-polysaccharide (Se-PS) and selenium-protein (Se-Pr). The results showed that the growth and selenium cumulation of O. sinensis at 25 mg/L Se⁶⁺ were the best with the  biomass and selenium levels reached 14.52 ± 0.82 g/L and 1644.83 ± 116.45 µg/g, respectively. Of those, the selenium composition in organic compounds was 568.84 ± 12.86 µg/g in Se-EPS, 429.68 ± 22.17µg/g in Se-PS and 443.19 ± 18.48 µg/g in Se-Pr. Moreover, the FT-IR analysis of the aforementioned compounds determined the presence of Se=O and C-O-Se stretching vibration at the featured absorption peaks. Consequently, these results have demonstrated that O. sinensis is capable to transform inorganic Se into organic Se forms during its development process. Finally, this study will create premises and scientific basis for the further study on the Se-enriched substances in O. sinensis mushroom.