Optimization Of Conditions For Growth And Polysaccharide Production By Hypsizigus Marmoreus In Liquid Cultivation

Hypsizigus marmoreus is a kind of rare edible fungi for its multi-function such as eliminating the oxygen free radicals from body, enhancing immunity, preventing aging and prolonging life. But the artificial cultivation of Hypsizigus marmoreus needs advanced cultivation techniques. Submerged liquid cultivation can effectively improve the main functional component of Hypsizigus marmoreus, the quantity and quality of polysaccharide can be both effectively enhanced. Submerged liquid cultivation can simplify the techniques, reduce production cost, shorten production cycle and increase the types of product processing. But there are fewer studies on submerged liquid cultivation and polysaccharide of Hypsizigus marmoreus at present. In order to obtain the optimum fermentation condition of Hypsizigus marmoreus, a strain having high growth speed and high polysaccharide yield was selected from 5 strains for nutrient condition optimization. Plackett-Burman design was used to select the key nutrient factors, a central composite experimental design and surface response methodology were employed to optimize the factor levels. Regularity and kinetic analysis of biomass growth and polysaccharide producing in the liquid culture have been studied in this paper. The main results are the following:(1)The strain ZJ-029 showed the highest growth speed and pick of saccharide production. It is the optimal strain for submerged liquid cultivation in the five strains.(2) In submerged cultivation, many nutrient variables and environmental conditions have great influence on the growth and polysaccharide production by Hypsizigus marmoreus ZJ-029. Glucose, maltose, cornstarch and bean cake powder showed significant influence on the mycelium growth of Hypsizigus marmoreus ZJ-029.Glucose, maltose and MgSO₄ were significant factors for the production polysaccharide outside cellular. Glucose, cornstarch and MgSO₄ were significant factors affecting the production of polysaccharide inside cellular. In the levels of PB design, the effect of each factor to each index showed positive effect. A central composite experimental design and surface response methodology were employed to optimize the levels of the four significant factors selected by PB design. Prediction models for dry cell weight (DCW), polysaccharide outside cells (EPS) and polysaccharide inside cells (IPS) under important nutrient conditions were developed by multiple regression analysis and verified. By solving the equations the optimal nutrient conditions for Hypsizigus marmoreus ZJ-029 in submerged liquid cultivation were obtained at 6.77g cornstarch/L, 36.57g glucose /L, 3.5g MgSO₄/L and 6.14g bean cake powder/L,10g maltose /L, KH₂PO₄ 3 g/L,MgSO₄ 3.5g/L, KNO₃ 1g/L,10mg/L VB 1,under which DCW ,EPS and IPS were 21.03g/L,9.62g/L and 1.47g/L, close to the highest value (20.9g/L,9.6g/L,1.5g/L )under their corresponding optimal conditions. These proof the equations are reasonable and feasible.(3) Optimal environmental conditions for Hypsizigus marmoreus ZJ-029 cultured in submerged liquid cultivation were obtained at 10% inoculation dose, 45ml medium in a 250ml flask, pH 6.5, 25oC and 180rpm according to the results of single-factor experiment design.8days after cultured,DCW ,EPS and IPS were17.7g/L,8.99g/L,1.92g/L respectively under the optimal nutritional and environmental conditions...