Study On Optimization Of Fermentation Conditions And Active Ingredients Of Cordyceps Gunnii Mycelium Selenium-riched

Selenium(Se),as an essential trace element and a cofactor of a mass of se-dependent enzymes,has received considerable attention due to its physiological functions.However,China is located in low selenium district,so that it is of especial significance for Se supplyment.Cordyceps has organic transformation capabilitiy of Se element,and many studies have shown that Se-polysaccharide from Se-accumulating mycelium possesses the activities of the polysaccharide and Se.But it is rarely reported about the effect of selenite on mycelium growth and Se-polysaccharide biosynthesis in submerged cultivation of Cordyceps gunnii.The aims of this paper were to study the characteristic of Se-resisting and Se-accumulating,to optimize the liquid fermentation conditions with Se absorption rate and biomass as index,and to analyse the structure and antioxidant activity of Se-polysaccharide.Solid plate culture was used for observing the colony characteristics and mycelium morphology of Cordyceps gunnii Se-riched.The results showed that the Se-resisting capability was 5 ?g/mL Na2SeO3 in solid medium,and Se could stimulate the growth of the strain and decrease the strain aging speed.The colony of Cordyceps gunnii was white,and mycelium was white,fluffy and pyknotic.Conidium had no diaphragm,ovoid and smooth,and adhered to the conidial fructification.Using atomic fluorescence method determinated the Se content of mycelium Se-riched,and to optimizate the fermentation conditions through the single factor and orthogonal test.The results were that the Se-resisting capability was 7 ?g/mL Na2SeO3 in liquid medium,and the optimal nutrition conditions were 6%sucrose,0.6%peptone,0.25%KH2PO4,0.20%MgSO4,pH 6.0,the initial pH 6.0,culture temperature 25?,inoculation quantity 8%.Under this condition,the biomass and the rate of Se-rich reached 11.657 g/L and 78.33%.The values of chemical constituents of normal Cordyceps guunii and Se-riched Cordyceps guunii were tested,for researching the effects of Se bio-enrichment to the functional and nutritional components of Cordyceps guunii.The results showed that four main kinds of nutrients and three kinds of active constituents of Se-riched Cordyceps guunii,of which the value of Se-polysaccharide reached 10.39%,was higher than normal Cordyceps guunii.Extracted,separated and purificated of uniform macromolecular polysaccharide from basic group mycelium and Se-rich mycelium respectively,and then named for CCPS-?(basic group)and SeCPS-?(Se-rich group).The amount of Se in the SeCPS-? and CCPS-? was 17.89 ?g/g and 2.01 ?g/g,respectively.Using GC,periodate oxidation,Smith degradation and NMR to analyze primary strcture,the results showed that the species of monosaccharide of CCPS-?was almost exactly as same as SeCPS-?,and they were both mainly composed of glucose,but the proportion of every monosaccharide was different;CCPS-? backbone was a-tape and mainly constituted by ?(1?4)glycosidic bonds.SeCPS-? backbone was mainly constituted by ?(1?4)glycosidic bonds,as well as a small amount of the ?-glycosidic bonds.SeCPS-? and CCPS-? were characterized by IR,and the results showed that SeCPS-? had the selenite group.Then,applying rotation meter,Congo red test and XRD to analyze its structure,the results showed that Se-rich had a certain influence on the structure.According to the antioxidant test in vitro,the abilities of CCPS-? and SeCPS-? for removing free radicals were evaluated.When the concentration of polysaccharide was 3.0 mg/mL,compared with CCPS-?,and the clearence rates of SeCPS-? towards hydroxyl radicals,DPPH,ABTS radicals and superoxide anion free radicals were respectively increased by 21.07%,3.64%,14.38%and 15.63%.The result showed that there was a strong ability of antioxidant for Se-polysaccharide.