Comparative Study On Structural Characteristics And Immune Activity Of Extracellular Polysaccharides From Liquid Fermentation Of Ganoderma Lucidum Parents And Their Hybrid Strains

Ganoderma lucidum polysaccharides have many biological activities,which are mainly obtained from fruiting bodies,spore powder,liquid fermentation mycelium and extracellular fluid.With the continuous development of biotechnology,because of the advantages of easy operation in the mutagenesis,screening and improvement of Ganoderma lucidum strains,and the advantages of short cycle and easy operation in obtaining Ganoderma lucidum polysaccharides from mycelium and extracellular fluid,the research on obtaining Ganoderma lucidum polysaccharides by submerged fermentation has received extensive attention.At present,there are few studies on Ganoderma lucidum polysaccharides from liquid fermentation.Among them,the research on polysaccharides produced by different strains mainly focuses on the change of fermentation characteristics,while the research on the difference between the content,structure and biological activity of extracellular polysaccharides from parents and their hybrid strains has not been reported.In this study,the extracellular polysaccharides of the parental strains G0119,G0154 and the hybrid strain GZ36 were used as the research objects.The molecular weight characteristics,monosaccharide composition,structural analysis,separation and purification and immune activity of different molecular weight polysaccharides were analyzed.The results are as follows :1.The content of different components in the extracellular polysaccharide produced by the parent and hybrid strains increased with the increase of fermentation time,and the extracellular polysaccharide produced by the hybrid strain GZ36 retained the same peak time components as the parent strains G0119 and G1054,and a new component P2 appeared.The molecular weight range of extracellular polysaccharide P1was 5.193×106~8.957×106g/mol after 72 h fermentation.The molecular weight of P3 ranged from 6.033×104 to 8.148×104 g/mol.The molecular weight of extracellular polysaccharide P2 from hybrid strain GZ36 was 4.437×106 g/mol.The extracellular polysaccharide 20 E component of the hybrid strain GZ36 showed certain advantages over the two parents in terms of yield.The yield of the extracellular polysaccharide 60 E component of the hybrid strain GZ36 was at a high level with the parental strain G0154,and the polysaccharide content was similar to the parental strain G0154.The extracellular polysaccharide 20 E components of the parental strain and the hybrid strain were mainly composed of glucose.The monosaccharide composition and proportion of the extracellular polysaccharide 20 E component of the hybrid strain GZ36 retained the characteristics of the monosaccharide composition of the corresponding component of the parental strain G0154.The exopolysaccharide 60 E component of the parental and hybrid strains was mainly composed of xylose.The exopolysaccharide 60 E component of the hybrid strain GZ36 retained the characteristics of the monosaccharide composition and proportion of the corresponding component of the parental strain G0154.2.The extracellular polysaccharide 20 E components of G0119,G0154 and GZ36 were all high molecular weight β-D-glucans with different molecular weights,but had the same primary structure repeat units.They were all glucans with β-(1→3)-glycosidic bond as the main chain and β-(1→6)-glycosidic bond as the branch chain,and the molar ratio of the main chain to the branch chain was 3:1.The aqueous solution process parameters of the high solubility extracellular polysaccharide 20 E component prepared by ionic liquid Emim Ac are as follows : the concentration of 20 E component in Emim Ac is 2wt %,the dissolution temperature is 90 °C,and the reaction time is 4 h.The solubility of 20 E component was increased to 0.25%(G0119),0.18%(G0154)and 0.20%(GZ36)by ionic liquid modification.The activity of NF-κB activated by 20 E component of extracellular polysaccharide of two parent strains(G0119,G0154)after solubilization of ionic liquid was improved.Compared with the negative control,when the final concentration was 50 μg/m L,the 20 E component of the hybrid strain GZ36 modified by ionic liquid had the activity of activating NF-κB.3.The extracellular polysaccharide 60 E components of G0119,G0154 and GZ36 were separated and purified by ion column chromatography to obtain two components of water phase and salt phase.The yield of salt phase components was higher.The yield of salt phase components of extracellular polysaccharide 60 E of G0119 and GZ36 was similar,which was 69.80% and 69.51%,respectively.The molecular weight analysis showed that the molecular weight of the water phase and the salt phase components and the 60 E component before purification was 100 thousand.The monosaccharide composition analysis showed that the water phase and salt phase components were mainly composed of xylose.The 60 E component before and after separation and purification showed certain activity compared with the negative control,and when the final concentration of polysaccharide was 50 μg·m L-1,the immune activity of the purified component was higher than that of the 60 E component before purification.