Screening Of Ganoderma Strains With High Intra-mycelial Polysaccharide Productivity And Physico-chemical Characteristic Study Of Polysaccharides

Twenty-five Ganoderma strains belonging to five Ganoderma species(Ganodermalucidum, GL; Ganoderma oerstedii, GO; Ganoderma resinaceum, GR; Ganodermasubamboinense, GS; Ganoderma tsugae, GT)were cultivated by using submergedliquid fermentation. Their mycelial biomasses were compared and the intra-mycelialpolysaccharides were further extracted using hot water and ethanol precipitation. Thepolysaccharide and protein contents were measured by using phenol-sulfuric acidmethod and Lowry method, respectively. The result showed that the total averagebiomass of 25 Ganoderma strains was 14.02±3.49 g/L, GR-1 strain produced thehighest biomass (20.52 g/L) while GT-3 strain produced the lowest (7.12g/L).Intra-mycelial polysaccharide yields of 25 strains were in a range of 0.10～0.55g/L infermentation broth. The highest was produced by strain GT-4 (0.55g/L) and the lowest(0.10 g/L) was by GS-2. Protein yields were from 0.05g/L to 0.68g/L and the averagewas at (0.28±0.18) g/L. Protein yield of GL-6 was the highest (0.68g/L) while that ofGT-1 was the lowest (0.10g/L). Strains (GL-1,GL-4,GL-6,GL-7 and GL-8) belongedto Ganoderma lucidum showed a favorable balance among biomass, polysaccharide andprotein yield.The monosaccharide compositions of intra-mycelial polysaccharides wereanalyzed by reverse phase HPLC with a condition capable to simultaneously detect 9monosaccharides. Samples were hydrolyzed by trifluoroacetic acid andmonosaccharides in hydrolyzates was derived with 1-phenyl-3-methyl-5-pyrazolone(PMP). The derivates were eluted with a phosphate buffered acetonitrile gradient on aC18 column and quantified. The results showed that all 25 intra-mycelialpolysaccharides contained glucose, galactose, mannose, glucosamine and fucose, andglucose was the major monosaccharide. Xylose and rhamaose were also detected inpolysaccharides from strain GL-3,GL-5,GL-6,GL-7,GO-3 ,GR-3,GR-4,GR-5,GT-1,GT-2,GT-3,GT-5,GS-2 and strain GL-5,GL-6,GL-7,GL-8,GO-3,GR-3,GR-4,GT-2,GT-3,GT-4,GT-5, respectively. Trace amount of galacturonic acidwas detected in strain GL-1,GL-3,GL-8,GR-3,GS-1,GT-1,GT-2,GT-3 ,GT-4 ,GT-5,GT-6,GT-7 polysaccharides,while no glucuronic acid was found.High performance gel permeation chromatography (HPGPC) analysis showed thatthe weight-mean molecular weights (MW) of all strains polysaccharides ranged from2.03×104 Da to 1.63×105 Da. MW of GR-1 polysaccharide was the biggest and that ofGS-1 was the lowest. Proteins were found to be associated with polysaccharides, and allthe samples tested possessed 3 to 4 peaks. The MW of majority peak was below5×104Da which accounted for 80.26% to 98.84% in total substances.