Ultrasonic disruption of fungal mycelia for efficient recovery of polysaccharide–protein complexes from viscous fermentation broth of a medicinal fungus

•Power ultrasound (US) was applied to medicinal fungus mycelial fermentation broth.•US was effective to disrupt the mycelia for viscosity reduction and product release.•US enhanced extraction yields of intracellular product and PSP from the broth.•US power and mycelial broth concentration were major factors on the PSP recovery.

High-intensity ultrasound (US) was applied to facilitate the extraction of intracellular and extracellular polysaccharide–protein complexes (PSPs) from the viscous mycelial fermentation broth of a medicinal fungus Cordyceps sinensis Cs-HK1. The US treatment caused the disruption of fungal mycelia, a dramatic reduction of the apparent broth viscosity, and the release of intracellular products into the liquid medium. The degree of mycelium disruption and the rate of intracellular product release were dependent on US power intensity, treatment period and biomass concentration of broth. The extraction or release kinetics of total water-soluble products and PSPs (yield Y versus time t) under the effect of US was fitted closely to the Elovich model Y = Yo + Y1 ln t and parabolic model Y = Yo + Y1t½, respectively. Another interesting effect of the US treatment was a notable increase in the antioxidant cytoprotective activity of PSP against H2O2 induced cell death.