Production, Isolation, Purification And Characterization Of Extracellular Polysaccharides Of Shiraia Sp. Under Submerged Fermentation

Stromata of Shiraia bambusicola were used as the folk medical fungus in China. There are theoretical and practical significances to study about the extraction, purification and characteristic of medicinal components of Shiraia bambusicola. This study investigated effects of culture medium and fermentation conditions on extracellular polysaccharide (EPS) production. Methods of extraction, separation and purification of soluble EPS were studied. Then the characteristics of EPS were also analyzed. The results were as follows:1) Orthogonal tests were carried out in this study and optimal culture medium were (g/L) glucose 50, corn steep liquor 3, KH2PO4 2, MgSO4·7H2O 0.10. The best condtions for EPS production were initial pH 6.0, temperature 30℃, liquid volume in flask 75 mL/250 mL and inoculation amount of 10% (v/v).The biomass and EPS yield could reach 11.7 g/L and 1.12 g/L, respectively.2) The optimized process of extraction, separation and purification of soluble EPS were supernatant of fermentation broth→alcohol precipitation, dried→redissolve→deproteinization by method of Sevag→dialysis→EPS→ion exchange chromatography by DEAE-52→gel chromatography by Sephadex G-200→single components: EPS1a, EPS2a and EPS3.3) The EPS of Shiraia bambusicola were water-soluble substance. There were no reducing end and continuous glycosideα(l→4) bonds. The properties and structures of EPS1a, EPS2a, EPS3 were similar. There were obvious characteristic IR absorption peaks of polysaccharide. There were no nucleic acid and protein in samples according to the data of ultraviolet scanning. EPS1a, EPS2a and EPS3 were mainly composed by glucose, mannose and galactose, however, the monosaccharide proportion of them were different.4) The EPS of Shiraia bambusicola had hydroxyl radical scavenging activities, Ec50 of EPS, EPS1a and EPS3 were 2.22 mg/mL, 2.37mg/mL, 4.30 mg/mL, respectively. The scavenge superoxide anion radical activity of EPS was not significant. EPS, EPS1a, EPS2a and EPS3 all had certain reducing power in the experiment.