Study On The Screening Of Ginkgo Biloba Endophytes And The Activities Of The Extracellular Polysaccharides

Ginkgo biloba is a kind of precious and unique medicinal and edible relict plant of China which contains a variety of activity ingredients such as flavonoids, lactones and polysaccharides. These components have prominent anti-oxidation, anti-tumor, immune regulation activities and other effects which are advantageous for health. Although Ginkgo biloba has the extensive ornamental and medicinal values, but it’s undeniable that the resource of Ginkgo biloba is limited and this constrains the development and application of its products. The fermentation of Ginkgo biloba endophytes can achieve the industrial production of the metabolites which are similar to the active ingredients in the host. In this paper, we screening the better strains by determining the in vitro anti-oxidant and antibacterial activities of the extracellular polysaccharides(EPSs). Preparing and comparing with the EPS and the Ginkgo biloba leaf polysaccharide(GBLP) on structure and properties for the possibility of industrial production.Through the screening experiments, we obtained a Ginkgo biloba endophytic bacterium named Endo Gin Ya6. Purified the EPS produced by the rescreening strain with anion exchange column chromatography DEAE-52 and gel exclusion chromatography Sephadex G-100. By modern instrumental analysis method to analyze EPS and GBLP’s structure, the characteristic peaks of infrared spectrum analysis showed characteristic absorption bands of polysaccharide; HPLC analysis showed that two polysaccharides has high purity, and the molecular weight were 13.2kDa and 12.08 kDa. GC-MS analysis showed that EPS and GBLP molar ratio of monosaccharide composition were different. 1H NMR and 13 C NMR spectrums showed that: Both EPSYa6 and GBLP were β-configuration pyranose with several terminal carbon signals which proved that different types of sugar residues were existed. Activity assays showed: two polysaccharides had inhibitory effect to the three indicator bacteria; In vitro antioxidant activity of EPS and GBLP were studied, and compared with the positive control VC. The results showed that, both of them had strong scavenging DPPH free radical and hydroxyl free radical abilities. In addition, the two polysaccharides aslo exhibited in vivo antioxidant activities, they can significantly improve the activities of SOD, GSH-Px and CAT.