Study On Fermentation Optimization And Anti-tumor Polysaccharide-peptide Of Grifola Frondosa GF9801

Grifola frondosa is a Basidiomycete fungus belonging to the order Aphyllopherales and family Polyporeceae. Its fruiting body is called"Huishu hua"in Chinese and"Maitake"in Japanese, which has recently attracted considerable attention for its various physiological activities, such as anti-tumor, anti-inflammatory, anti-oxidant, hypoglycemic, hypocholesterolemic and immuno-stimulating activities. In this work, based on the preliminary experiments of our lab, we attempted to systematically to further optimize the medium composition of significant factors to increase the yields of mycelial biomass and exo-polymer of Grifola frondosa GF9801 using response surface methodology, to study the effects of cultivation agitation intensity and aeration rate on the production of mycelial biomass and exo-polymer in a 15 L batch fermenter, and to investigate the separation, bioactivity-directed fractionation, purification and structural analysis of the anti-tumor active polysaccharide fraction GFPS1b and its mechanism in vivo and in vitro.Based on the preliminary experiments, a three-level Box-Behnken factorial design was employed combining with response surface methodology (RSM) to optimize the medium composition for the production of the mycelial biomass and exo-polymer in submerged cultures by Grifola frondosa GF9801. A mathematical model was then developed to show the effect of each medium composition and their interactions on the production of mycelial biomass and exo-polymer. The model estimated that, a maximal yield of mycelial biomass (17.61 g/L) could be obtained when the concentrations of glucose, KH₂PO₄, peptone were set at 45.2 g/L, 2.97 g/L, 6.58 g/L, respectively; while a maximal exo-polymer yield (1.326 g/L) could be achieved when setting concentrations of glucose, KH₂PO₄, peptone at 58.6 g/L, 4.06 g/L and 3.79 g/L, respectively. These predicted values were also verified by validation experiments. Compared with the values obtained by other runs in the experimental design, the optimized medium resulted in a significant increase in the yields of mycelial biomass and exo-polymer. Maximum mycelial biomass yield of 22.50 g/L was achieved in a 15-l fermenter using the optimized medium.The effects of cultivation agitation intensity and aeration rate on the production of mycelial biomass and exo-polymer by Grifola frondosa GF9801 in a 15 L batch fermenter were further investigated. Results revealed that agitation intensity and aeration rate could significantly influence the production of mycelial biomass and exo-polymer, the levels of dissolved oxygen and reducing sugars, and the broth apparent viscosities. The highest mycelial biomass (23.95 g/L) and exo-polymer production (1.421 g/L) were obtained at the...