Statistical optimization of media for extracellular polysaccharide by Pholiota squarrosa(Pers.ex Fr.)Quel.AS 5.245 under submerged cultivation

摘要

In the present investigation,response surface methodology based on a five-level,six-factor central composite rotatable design of experiments was employed to optimize the levels of six factors significantly affecting the yield of extracellular polysaccharide produced by submerged cultivation using Pholiota squarrosa(Pers.ex Fr.)Quel.AS 5.245.The selected factors,i.e.,yeast extract,fructose,magnesium sulfate,maltose,zinc chloride and initial pH value were based on the results of our previous Plackett-Burman design.By solving the quadratic regression equation using appropriate statistic methods,the optimum concentration values for obtaining 876.32 mug extracellular polysaccharide per milliliter of cultivation medium were determined:yeast extract 6.0 g 1~(-1),fructose 11.5 g 1~(-1),magnesium sulfate 0.5 g 1~(-1),maltose 9.6 gl~(-1),zinc chloride 38.6 mg l~(-1)and initial pH value 5.3.The validation data under various experimental conditions have also confirmed the correlation between the experimental and theoretical values.