Solid-state cultivation of Grifola frondosa (Dicks: Fr) S.F. Gray biomass and immunostimulatory effects of fungal intra- and extracellular beta-polysaccharides.

Grifola frondosa strain GF3, was cultivated on solid-state substrate consisting of milled whole corn plant (Zea mays) and olive press cake supplemented with mineral additives and olive oil. Maintenance of the moisture content in the solid substrate is of crucial importance. Moistures higher than 70% promote growth of G. frondosa mycelium and polysaccharide production. Four fractions of pure extracellular beta-D-glucans with total mass 127.2mg and four fractions of intracellular polysaccharides with total mass 47.2mg were isolated. Polysaccharides were further separated by ion-exchange, gel and affinity chromatography. Isolated polysaccharide fractions from fungal mycelium proved to induce moderate amounts of TNF-alpha in PBMC cells in vitro. The extent of TNF-alpha induction was up to 322pgmL(-1) at a polysaccharide concentration of 200microgmL(-1) for the intracellular fraction. The TNF-alpha inducing activity is comparable to romurtide, which has been used as a supporting therapy in cancer patients treated with radiotherapy and/or chemotherapy.