Mycelial fermentation characteristics and anti-fatigue activities of a Chinese caterpillar fungus, Ophiocordyceps sinensis strain Cs-HK1 (Ascomycetes).

Abstract

Mycelial fermentation of an Ophiocordyceps sinensis strain Cs-HK1 was carried out in various volumes of stirred-tank fermenters from 1.6-L and 15-L laboratory scale to 2000-L industrial scale. The mycelial growth in most fermenters had a higher rate, due probably to more efficient oxygen supply, than in shake-flasks. The mycelial fermentation was successfully scaled up to 2000-L industrial fermenters, achieving 30 g/L maximum biomass in 5 days. The Cs-HK1 mycelia formed hairy and fluffy pellets in the fermentation medium and the mycelial broth exhibited pseudoplastic rheology following the power law, with the flow behavior index n decreasing from 0.5 to 0.3, and the flow consistency K and the apparent viscosity µα increasing with time and biomass concentration. The mycelial broth containing biomass and extracellular products harvested from 2000-L fermenters was tested for anti-fatigue activities in forced animal swimming experiments. The mycelium hot water extract showed the most significant effects, increasing the swimming endurance of mice up to 100%, and also increasing the glycogen levels and reducing the lactic acid and blood urea nitrogen levels significantly. The results demonstrated the feasibility of Cs-HK1 mycelial fermentation for large-scale production of bioactive and medicinal materials.