Isolation,Purification And Activity Analysis Of Exopolysaccharides From Candida Guilliermind

Polysaccharide is an important basic substance in living organisms. It plays a significant role in regulating cell activity. Polysaccharide has a wide range of pharmacological activity,and it has a great effect on the human health. Marine microorganisms are in the special environment of low temperature, high salt, high pressure and less nutrient, and have potential to generate new polysaccharides with novel structure and unique function. Therefore, it has become one of the important strategies for the development of new resources to find new active polysaccharides from marine microorganisms.In order to study the productivity, physicochemical property, component and activity, the exopolysaccharides were extracted from the fermentation culture of Candida guilliermind which was isolated from sea cucumber intestine in this study. The fermentation liquor was treated with ethanol and Sevag reagent to obtain the crude exopolysaccharide(EPS). The productivity of EPS was 0.137 g/L and the purity measured by the phenol-sulfuric acid method was 48.78%. Meanwhile, the protein content of EPS measured by the Coomassie brilliant blue method was 1.45%. Gas chromatography was employed for the component analysis of EPS and the antioxidant activity of EPS was studied in vitro. The results indicated that EPS consists of xylose, mannose, glucose and galactose, in which the molar ratio is1.00: 41.60: 7.17: 3.21. The EPS can scavenge ·OH radical and O2-· radical efficiently and possessed some reducing power. The experiments of immune and antioxidant activity in vivo were done via measuring the effect of EPS on alkaline phosphatase(AKP), lysozyme(LSZ),superoxide dismutase(SOD), catalase enzyme(CAT) activity and malondialdehyde(MDA)content by injecting EPS solution in sea cucumber body. The results showed that EPS could increase the activity of AKP, LSZ, SOD, CAT in different extent, and decrease the content of MDA significantly in sea cucumber coelomic fluid.EPS has higher effective biological activity, thus it is worth of further purification and analysis. Three components(EPS1, EPS2, EPS3) were separated by Sepharose anion exchange chromatography. The antioxidant activity of EPS2 was found more potent compared to the other two components. The purified exopolysaccharides(EPS2-1) were obtained bySephacryal chromatography. Gas chromatography was used for the component analysis of EPS2-1 and the antioxidant activity of EPS2-1 was studied in vitro. The results indicated that EPS2-1 was composed of xylose, mannose, glucose, and galactose, in which the molar ratio was 1.00: 35.98: 1.22: 1.68. Moreover, EPS2-1 possessed the strong antioxidant activity. The scavenging rate of ·OH radical could reach to 100% when the EPS2-1 concentration was0.36 mg/mL. This result is much higher than that of Vc(14.42%) at the same concentration.When the EPS2-1 concentration reached to 0.60 mg/mL, the scavenging rate of O2-· radical was about 53.22%. Meanwhile, the EPS2-1 also had some reducing power. Based on above results, these active polysaccharides have more application potential for further study and development.