Statistical optimization of media for mycelial growth and exo-polysaccharide production by Lentinus edodes and a kinetic model study of two growth morphologies

Lentinus edodes (shiitake mushroom) is a well-known medicinal and edible mushroom throughout the world. Statistical optimization was employed to optimize the culture medium for maximum mycelial growth and exo-polysaccharide (EPS) production in submerged fermentation: Plackett–Burman design (PBD) was applied to determine significant factors, followed by the paths of steepest ascent to move to the general vicinity of the optimum and Box–Behnken design (BBD) to obtain the final optimum culture medium composition. Glucose, yeast-powder and pH were significant for fermentation. 15.4 g glucose and 5.32 g yeast-powder per liter and pH 4.61 were optimum for the biomass accumulation from 2.75 g/l to 6.88 g/l, while 15.78 g glucose and 5.86 g yeast-powder per liter and pH 4.48 were optimum for EPS production from 0.214 g/l to 0.751 g/l. Under the optimized cultivation condition, cultivation kinetic models were studied in flask (pellet growth form) and airlift (filamentous growth form) reactors. The two morphologies resulted in different culture processes and mathematical models.