Characterization of three extracellular polysaccharides from Shiraia sp. Super-H168 under submerged fermentation

Three extracellular polysaccharides (SP-1, SP-2 and SP-3) from Shiraia sp. Super-H168 under submerged fermentation were purified by using ethanol precipitation, chromatography separation on the DEAE-cellulose-32 column and the Sephadex G100 column. The molecular weights of SP-1, SP-2 and SP-3 were determined to be approximately 189 kDa, 130 kDa and 52 kDa, respectively. Monosaccharide analysis revealed that SP-1 was composed of mannose and glucose in molar ratios of 1:28.47, and SP-2 and SP-3 were both composed of mannose, glucose and galactose in molar ratios of 63.32:70.06:1 and 2.31:14.69:1, respectively. Three polysaccharides had very weak scavenging activity of superoxide radical (<3%), the hydroxyl radical scavenging activities of SP-1, SP-2 and SP-3 being 86.5%, 19.8% and 60.5%, respectively. SP-2 showed the strongest reducing power, and the reducing power of SP-3 was the weakest.