Fermentation Optimization And Structure-activity Relationship Of Extracellular Polysaccharide In Three Macro Funguses

Research on fungal polysaccharides is in ascendant, some rare wild fungus have been discovered and studied.Studies about three wild fungus:Ginkgo Poly-pores,[rigidoporus microporus(Fr.)Overh.],Steccherinum septentrionale (Fr.) Bank.have not yet been reported.Ginkgo polypores strains(collected from the Changbai Mountains) was identified atthe level of molecular biology. And three fungus were carried submerged fermentation experiments.The relationship between extracellular polysaccharide,mycelial dry weight,microscopic morphology and rheological properties was preliminary explored in the liquid fermentation conditions. Collected by liquid submerged fermentation, extracellularpolysaccharide was refined by Sevage method,gel column chromatography.The structure-activity relationship of the three fungi extracellular polysaccharide was studied by infrared spectrum analysis, gas chromatography, TGA experiments, Congo red experiments,specific viscosity measurement and antioxidant experiment in vitro. The experimentalresults are as follows:1. Species identificationGinkgo polypores was identified in molecular biology level by ITS technology, andphylogenetic tree was constructed for identification of the wild fungi. The DNA sequence ofITS region for ginkgo Polypores was submitted to GenBank (http://www.ncbi.nlm.nih.gov/),which won a number of genes: KF279536. Similar classified ITS gene sequences weredownloaded from GenBank, A preliminary comparison of these ITS series, constructingphylogenetic trees, shows that the wild fungi belongs to Fomitopsis genera.2. Submerged fermentation experimentsSingle-factor experiments were executed, and confirmed the optimal ferment-ation time,were8d,6d,8d,respectively;the optimal Carbon source,lactose,lactose,maltose,respectively,the optimum Nitrogen source, yeast powder, tryptone, soybean powder,respectively.And in the basis of single-factor experiments, submerged fermentation in5-L fermenter was conducted to explore the extracellular polysaccharide, mycelium dry weight, microscopic morphology and rheological properties,the ball mycelium morphology and rhe ology has found inter-conditional relationship of mutual influence and restraint.3、Purification, Structure and function of extracellular polysaccharide in vitroBy filtration and ethanol precipitation, enough extracellular polysaccharide wascollected,the protein was removed through Sevage law,and purification of polysaccharide wasget by Sepharose CL-6B gel chromatography.1、Infrared analysis showed that in addition tothe typical polysaccharide absorption peaks, the extracellular polysaccharide of GinkgoPolypores have pyran ring and a carboxylic acid group; the extracellular polysaccharide of[rigidoporus microporus(Fr.)Overh.] exist α-and β-glycosidic bond; Steccherinumseptentrionale (Fr.) Bank. exists β-glucuronidase and mannose structures.2、GC analysisshowed that the extracellular polysaccharide of Ginkgo polypores are mainly composed ofmannopyranose (59.32%), galactopyranose (12.71%) and glucose (11.02%) composed;monosaccharide composition of [rigidoporus microporus(Fr.)Overh.] glucose (50.09%),mannose (28.53%) and galactose (15.83%); the extracellular polysaccharide of Steccherinumseptentrionale (Fr.) Bank. are mainly composed of glucose, accounting for98.05%.3、thermalgravimetric experiment shows at the temperature101℃112.11℃and132.49℃,theextracellular polysaccharide of the three strains was not lost.4、Congo red experiments shows，extracellular polysaccharide of [rigidoporus microporus(Fr.)Overh.] can form complexes withCongo red, proving the existence of triple helix random coil chain in its advanced structure,while Fomitopsis sp. and Steccherinum septentrionale (Fr.) Bank. funguse are not theexistence of this structure.5、specifically viscosity of the extracellular polysaccharides byUbbelohde viscometer are274mL/g,334mL/g and543mL/g respectively.6、The antioxidantexperiments in vitro showed that, extracellular polysaccharides of three wild fungi have someantioxidant activity, but the differences are significant. Extracellular polysaccharide of Ginkgopolypores has lower DPPH clearance rate,When polysaccharide concentration was2.5mg/mL,DPPH clearance rate was10.02%.But the clearance rate of OH radicals is highest(37.99),when polysaccharide concentration is4mg/mL,As for [rigidoporus microporus(Fr.)Overh.],scavenging rate DPPH and OH radical is lower(8.75%and4.37%respectively,DPPH, OHradical scavenging rates for extracellular polysaccharides of Steccherinum septentrionale (Fr.)Bank. are relatively higher, when the concentration of the polysaccharide is3mg/mL, radicalsthe clearance rate of DPPH, OH are24.43%,47.45%, respectively.Through these experiments, we learned the position of Ginkgo polypores in the fungaltaxonomy,identified morphology、rheology changes of three strains wild fungi in submerged fermentation process,the structure-activity relationship of extracellular polysaccharide. Thislaid an important theoretical basis for wild fungi in industrialization process.