Optimization of Cultivation Conditions for Extracellular Polysaccharide and Mycelium Biomass by Pholiota Squarrosa / 微生物学通报

ABSTRACT

Response surface methodology (RSM) based on a three-level three-factor Box-Behnken design of experiments was used to optimize the extracellular polysaccharide content and the mycelium biomass by submerged cultivation using Pholiota squarrosa AS 5.245. The critical factors selected for the investigation were temperature, time of cultivation and volume of medium, based on the results of our previous Plackett-Burman design. The objectives of this present work were to locate optimum levels of these process parameters, and to find out interactions among them for enhancement of the yield of extracellular polysaccharide and mycelium biomass. By solving the regression equation and also by analyzing the response surface contour plots, the optimal process conditions were determined under conditions of temperature, 28.07℃; cultivation time, 8.79 d and volume of medium, 68.51 mL, the prediction of extracellular polysaccharide content (EPC) by Pholiota squarrosa AS 5.245 was 1062.69 ?g per milliliter of fermentation liquor. While cultivation temperature, time and volume of medium were 27.60℃, 9.42 d and 54.20 mL respectively, the mycelium biomass expressed as dry cell weight (DCW) was 11.32 mg?mL -1. In order to simultaneously obtain the maximum yield of EPC and DCW, the above conditions would be located at 27.62℃, 9.19 d and 64.10 mL. In these conditions, the maximum predicted yield of EPC and DCW were found to be 1050.64 ?g?mL -1 and 11.10 mg?mL -1, respectively. These predicted values were also verified by validation experiment.