An Extractive Study Of The Acetylated β-1,6-giucan From Umbilicaria Esculenta (Miyoshi) Minks And Its Feasibility Study Of Application

Polysaccharide is a kind of natural polymer polymerized with large quantities ofmonosaccharide molecules (usually more than10) combined with glycosidic bond, which isthe substantial matter that maintains the essential activities of life. Polysaccharide existswidespreadly in animals, plants, microorganism (bacteria and fungi). The bioactive effects ofthe polysaccharide, such as antitumor effect, antiviral effect, antiradiation effect, anti-bacterialeffect, antioxidation effect and so on, are realized by enhancing the immunity of the body. Thelichen is symbiotic organism composed of a fungus partner, the mycobiont, and may be eithera green alga or a cyanobacterium, the photobiont. Most of the fungus-partners areascomycetes and some are basidiomycetes. Lichen contains many chemical constituentswhich have the pharmacological activities. The bioactive substances mainly are lichenic acidsand polysacchrides, which have immunomodulatory effects, antitumor effects, and so on. Theantitumor activity of the partly acetylated β-1,6-glucan from Umbilicaria esculenta wasproved higher than those not being acetylated glucans, which triggered the hotspot researchon the glucan from Umbilicaria esculenta. However, due to the slow growth of lichens,over-collection can easily cause the extinction of lichens and it is unable to explore and utilizethe lichenan through lichens. Therefore, an alternative material is urgently needed. Studieshave showed that most of lichen polysaccharides were produced by the mycobionts. Besides,under the optimized culture conditions, the growth rate of the lichen-forming fungus isrelatively faster than the growth rate of lichens and the lichen-forming fungus can be culturedalone, so isolating, culturing and then fermenting the mycobionts of lichen will be an effectiveand sustained way to obtain massive pustulan from Umbilicaria esculenta. Based on theobjective, the purpose of this thesis is to conduct the explorative prophase research of themassive industrial producting pathway of the partly acetylated β-1,6-glucan. Through optimizing the initial liquid culture conditions, the results showed the bestcarbon sources for the mycobiont of Umbilicaria esculenta were mannitol and sorbitol and theoptimum nitrogen condition were no extra nitrogen sources based on the potato extracting.The optimal cultivation temperature was about18C while the optimal cultivation speed was180rpm. Meanwhile, through the original method and the improved method of Shibata’sacetylated β-1,6-glucan-extracting method (1968), the acetylated β-1,6-glucans wereextracting from Umbilicaria esculenta lichen and two liquid culture mediums of theUmbilicaria esculenta mycobiont. The polysaccharides content of the crude pustulanextracted from Umbilicaria esculenta lichen was about98.43%and the final yield rate ofpustulan was approximately2.5%; the crude pustulan extracted from PDA liquid mediumcontained92.4%polysaccharides while the final pustulan extracting rate was calculated asabout86mg/L; the crude pustulan extracted from LB liquid medium contained about94.85%polysaccharides and the yield of the pustulan was about72mg/L.Unlike previous studies only using lichens as experimental material for extracting theacetylated β-1,6-glucans, this thesis used two kinds of liquid culture to cultivate themycobiont of Umbilicaria esculenta and extracted the partly acetylated β-1,6-glucans fromthem. The LB culture medium did not contain any exogenous polysaccharides, and the crudepustulan did not contain any starch. The only inadequacy was the low yield rate which needthe subsequent reasearchers to optimize the liquid culture of the mycobiont of Umbilicariaesculenta based on the LB culture medium and enhance the growth rate to obtain moreacetylated β-1,6-glucan so that can lay a real solid foundation of the the massive industrialproducting pathway.