Fermentation And Application Of Exopolysacchairdes Produced By Three Kinds Of Edible And Medicinal Fungi

In this experiment, three edible and medicinal fungi were applied,and theoptimization of submerged culture used for EPS production was investigated. TheEPS was isolated and purified from culture broth and its physico-chemicalcharacterization of purified EPS was determined by GC, FT-IR and TGA. Finally, theantioxidation potential of EPS in vitro and application in tobacco was investigated.Three species of fungi were Daedalea dickinsii, Boletus aereus, Pleurotuspulmonarius.The exopolysaccharide (EPS) production by Daedalea dickinsii in submergedculture was optimized. The suggested medium composition for EPS production wasas follows:50g/L maltose,5g/Lsoy peptone,5mM CaCl2,28℃,pH6. Daedaleadickinsii was cultured20d under the optimized culture conditions in a5-Lstirred-tank reactor, the maximum concentration of EPS was4.52g/L at13d.Furthermore, the morphological parameters of the pellets and the broth viscosity werecharacterized in a5-L stirred-tank fermenter, which was proved that EPS yield may bethe critical parameters affecting mycelial morphology and broth viscosity. After EPSwas deproteinized by Sevag method, one group of EPS was obtained from the culturefiltrates by gel filtration chromatography on Sepharose CL-6B. FT-IR spectralanalysis revealed that the purified EPS had similar characteristic of Mannose.GCanalysis showed that the purified EPS was mainly composed of Allose. Furthermore,thermo gravimetric analysis (TGA) indicated the degradation temperature (Td) of thepurified EPS was found to be189oC. The EPS fraction had a very high antioxidantactivity, there was linear relationship between antioxidant activity and concentrationof EPS. Finally, The transfer rate of Daedalea dickinsii EPS in cigarette smoke was1.36%～1.95%. The results of sensory experiments suggested that optimal additionconcentration of EPS in cigarette was0.06%.Boletus aereus, the suggested medium composition for EPS production was asfollows:50g/L of Sucrose, Yeast extract5g/L, the optimum temperature was25oC,with initial pH6. Under the optimized culture conditions in a stirred-tank reactor,The maximum concentration of EPS was1.84g/L on5th day. The viscosity andmycelium of various indicators had certain correlation among1-10d. Three groups ofEPSs (designated as Fr-I、Fr-II、Fr-III) were isolated by gel filtration chromatographyusing Sepharose CL-6B. Fr-I was composed of10monosaccharides, Fr-II was composed of13monosaccharides, and Fr-III was composed of13monosaccharidestoo, The thermal stability of Fr-I was higher than Fr-II and Fr-III, thermo gravimetricanalysis (TGA) indicated the degradation temperature (Td) of the Fr-I was found to be170oC, while Fr-II and Fr-III respectively at156oC and155oC. The results showedthat Boletus aereus had a very high antioxidant activity. The highest transfer rate ofpolysaccharide was2.01%with0.6g/pipe of the EPS concentration.The suggested medium composition for EPS production of Pleurotuspulmonarius was as follows:60g/L sucrose,6g/L soy extract and5mM KH2PO4.25oC, pH5. Under the optimized culture conditions, the maximum concentration of EPSwas3.745g/L on7th day. Furthermore, the morphological parameters of the pelletsand the broth viscosity were characterized in a5-L stirred-tank fermenter. It wasproved that mycelial morphology and broth viscosity may be the critical parametersaffecting EPS yield. After EPS was deproteinized by Sevag method, one group of EPSwas obtained from the culture filtrates by gel filtration chromatography on SepharoseCL-6B. FT-IR spectral analysis of the purified EPS showed that it was a acidicpolysaccharide rich in glucose and mannose. GC analysis showed that the purifiedEPS was mainly composed of galactose and glucose. Furthermore, the degradationtemperature (Td) of the purified EPS was found to be217oC by thermo gravimetricanalysis (TGA). The EPS transfer rate in the smoke and EPS content showed positivecorrelation.