Optimization of Extraction Technology of Extracellular Polysaccharide from Fermentation Broth Ganoderma atrum and Study on Its Antioxidant Activity in vitro

The content of polysaccharide of Ganoderma atrum was determined by the method of improved phenol-sulphate acid.On the basis of single-factor tests,orthogonal design was applied to analyze the effects of ethanol concentration,extraction time and broth pH value on the extraction rate of polysaccharides.The results showed that the optimum ethanol concentration,extraction time and broth pH value are 80%,19 h,and 5.5,respectively.Under these conditions,the extraction yield of extracellular polysaccharide is 5.2343 g/L.At the concentration of 40 mg/ml,the hydroxyl and DPPH radicals-scavenging activities of the polysaccharide are 39.85% and 23.4%,respectively.It indicated that the extracellular polysaccharide produced by Ganoderma atrum has a significant antioxidant activity.