OPTIMAL CONDITIONS FOR THE GROWTH AND POLYSACCHARIDE PRODUCTION BYHYPSIZIGUS MARMOREUSIN SUBMERGED CULTURE

ABSTRACTS In submerged cultivation, many nutrient variables and environmental conditions have great influence on the growth and polysaccharide production by Hypsizigus marmoreus. Plackett–Burman design was used to determine the important nutrient factors. A central composite experimental design and surface response methodology were employed to optimize the factor levels. 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 highest EPS production (9.62 g/L) were obtained at 6.77 g cornstarch/L, 36.57 g glucose/L, 3.5 g MgSO4/L and 6.14 g bean cake powder/L, under which DCW and IPS were 16.2 g/L and 1.46 g/L, close to the highest value under their corresponding optimal conditions. Optimal environmental conditions were obtained at 10% inoculation dose, 45 mL medium in a 250 mL flask, pH 6.5, 25C and 200 rpm according to the results of single-factor experiment design. PRACTICAL APPLICATIONS Hypsizigus marmoreus polysaccharides have many functional properties, including antitumor, antifungal and antiproliferative activities, and free-radical scavenging. Liquid cultivation could produce a higher yield of polysaccharides and more flexible sequential processing methods of H. marmoreus, compared with traditional solid-state cultivation. However, the cell growth and production of polysaccharides would be influenced by many factors, including nutrient conditions and environmental conditions in the liquid cultivation of H. marmoreus. Keeping the conditions at optimal levels can maximize the yield of polysaccharides. The study not only found out the optimal nutrient conditions and environmental conditions for highest cell growth and yield of polysaccharides, but also developed prediction models for these parameters with important nutrient variables. Yield of polysaccharide inside of cells was also studied as well as polysaccharides outside of cells and cell growth. The results provide essential information for production of H. marmoreus polysaccharides by liquid culture.