Study On Optimization Of Culture Conditions And Antioxidant Activity Of Ophiocordyceps Xuefengensis

Objective:To explore the optimum medium and fermentation conditions for Ophiocordyceps xuefengensis liquid fermentation,study on the dynamic accumulation of metabolites in the submerged fermentation of Ophiocordyceps xuefengensis,preliminary study on the antioxidant activity of intracellular polysaccharides and extracellularpolysaccharidesproducedbysubmergedfermentationof Ophiocordyceps xuefengensis.Method:The Ophiocordyceps xuefengensis was divided into carbon source,nitrogen source,vitamin group and pH group,liquid fermentation,shaking culture for 6 days,deal with the samples,then using phenol sulfuric acid method to determine the intracellular polysaccharide and extracellular polysaccharide,with sodium periodate colorimetric determination of intracellular cordyceptic acid,vanillin perchloric acid colorimetric method for the determination of intracellular total three terpene.In the course of expanding culture of Ophiocordyceps xuefengensis,the changes of pH value,biomass,intracellular and extracellular polysaccharide,Intracellular cordyceps acid and total three terpene in the Ophiocordyceps xuefengensis were determined.Extraction of polysaccharides by water extraction and alcohol precipitation method,intracellular polysaccharides and extracellular polysaccharides were obtained after the removal of protein,study on the intracellular polysaccharide and extracellular polysaccharide of Ophiocordyceps xuefengensis by infrared spectroscopy,the adjacent benzene three phenol autoxidation method to determination of intracellular polysaccharides and extracellular polysaccharides on superoxide anion free radical scavenging effect,determination of hydroxyl free radical?OH?scavenging capacity of intracellular polysaccharide and extracellular polysaccharide by phenanthroline-Fe²⁺oxidation method,DPPH method was used to determine the scavenging ability of DPPH free radicals in intracellular polysaccharides and extracellular polysaccharides.Results:In the carbon source group,the biomass,Intracellular cordyceps acid and intracellular total amount of three terpene of sucrose group were the highest,respectively 3.51g/L,314.96mg/g and 8.97 mg/g,the content of intracellular polysaccharide and extracellular polysaccharide in the starch group was the highest,respectively 54.18 mg/g and 17.08 g/L.In the group of nitrogen source,yeast extract powder group of extracellular polysaccharide and intracellular polysaccharide and intracellular total amount of three terpene are the highest,respectively 2.20g/L,76.29mg/L,8.76mg/g,yeast extract group had the highest biomass and Intracellular cordyceps acid,respectively 10.83g/L,149.59mg/g,in the vitamin B group,vitamin B1 group biomass,extracellular polysaccharide and intracellular polysaccharide and intracellular cordyceps acid are the highest,respectively 2.50 g/L,0.87 g/L,30.05mg/g,424.59 mg/g,vitamin B complex group of intracellular total three terpene is the highest,12.41 mg/g,in the initial medium pH group,in pH 8 can reap the greatest biomass,intracellular polysaccharide and intracellular cordyceps acid,respectively3.49 g/L,32.10 mg/L and 283.85mg/L,and pH 7 can gain the highest intracellular total amount of three terpene,20.32mg/g,when the pH value is 5 extracellular polysaccharide is the highest,1.05 g/L.In the continuous sampling process,the 93h biomass reached a maximum of 12.77 g/L,the 105h intracellular total amount of three terpene reached a maximum of 21.97mg/g,the 93h intracellular polysaccharide reached a maximum of 81.80 mg/g,the 81h Intracellular cordyceps acid reached a maximum of 453.01 mg/g,the 141h extracellular polysaccharide reached a maximum of 2.91 mg/L in,the pH value of fermentation broth reached the lowest value at 93h,6.4.The infrared spectra of the extracellular polysaccharide of the Ophiocordyceps xuefengensis had absorption peaks at 3326 cm^-1 and 2939 cm^-1,and the infrared spectrum of the intracellular polysaccharide of the Ophiocordyceps xuefengensis had absorption peaks at 3292 cm^-1 and 2936 cm^-1.Intracellular polysaccharides and extracellular polysaccharides on DPPH radical scavenging rate respectively reach62.70%and 57.82%respectively,intracellular polysaccharide and extracellular polysaccharide on hydroxyl radical scavenging rate respectively reach 64.43%and59.95%respectively,intracellular polysaccharide and extracellular polysaccharides on superoxide anion free radical scavenging rate respectively reach 60.56%and 52.01%.Conclusion:?1?The biomass,intracellular and extracellular polysaccharide,Intracellular cordyceps acid and total three terpene in the cell were taken as indexes,after comprehensive analysis,the best carbon source for the fermentation of Ophiocordyceps xuefengensis was sucrose,the most suitable nitrogen source was yeast extract powder,the most suitable vitamin was vitamin B1,the most suitable medium pH was 8.?2?With the prolonging of fermentation time,the content of biomass and intracellular total amount of three terpene are first increased and then decreased.The content of intracellular polysaccharide,intracellular cordyceps acid were first increased and then decreased to a relatively stable value,extracellular polysaccharide increased first and then kept at a stable value,fermentation pH values increased with fermentation time decrease first and then continue to rise.Compared with the results of single factor experiments,the yield of biomass,intracellular polysaccharide,extracellular polysaccharide,intracellular cordyceps acid and intracellular total amount of three terpene were increased.?3?The results of infrared spectra of the intracellular polysaccharides and extracellular polysaccharides from the Ophiocordyceps xuefengensis were similar,and the two had the characteristic absorption peak of polysaccharide.?4?The intracellular polysaccharide and extracellular polysaccharide of the Ophiocordyceps xuefengensis had antioxidant activity,but the antioxidant activity of intracellular polysaccharide and extracellular polysaccharide was different,the antioxidant activity of intracellular polysaccharide was better than that of extracellular polysaccharide.