Immunostimulatory effects of fungal polysaccharides from Ganoderma lucidum submerged biomass cultivation

A Slovenian Ganoderma lucidum strain MZKI G97 was isolated and cultivated in a 10 L stirred tank reactor, on potato dextrose substrate. Biomass up to 15.2 g L-1 and fungal polysaccharides were produced. The extracellular polysaccharide fraction was obtained by the precipitation method with ethanol. Four intracellular polysaccharide fractions were obtained by the hot-water extraction and precipitation with ethanol, by ammonium oxalate extraction, and by extraction with sodium hydroxide, followed by precipitation with acetic acid and precipitation with ethanol. Immunostimulatory effects of isolates were tested on induction of cytokine (TNF-alpha, IFN-gamma) synthesis in primary cultures of human mononuclear cells (PBMC) isolated from a buffy coat. Results have shown the potential of isolates to induce moderate amounts of TNF-alpha (max. 630 pg mL(-1) of a culture supernatant), and IFN-gamma in trace amounts (max. 11.5 pg mL(-1)), respectively. 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.