| Selenium(Se)is used for the synthesis of selenoenzyme in living organisms.Cordyceps can promote the organic conversion of selenium in the body.The addition of selenium to Cordyceps has the dual activity of edible fungi and selenium.However,there are relatively few studies on the growth and metabolism of Cordyceps militaris at home and abroad.In this paper,the growth and metabolism of Cordyceps militaris were studied.The effects of selenium on the growth and metabolism of Cordyceps militaris were studied by using mycelial biomass,active constituents,polysaccharide content and organic acid as indicators.Based on the study,the effects of selenium on the antioxidant enzymes of Cordyceps militaris and the key enzymes of polysaccharide synthesis and metabolism were studied.Through liquid fermentation experiments,the best selenium source was determined to be sodium selenite.The concentration of sodium selenite resistant to Cordyceps militaris was 7 μg/mL,and the biomass of selenium-enriched Cordyceps sinensis was 13.190 g/L,compared with the control group.(10.32 g/L),an increase of 28.01%.The colony characteristics of the basic group(blank group)and the selenium-added group(7 μg/mL sodium selenite group)were observed by solid plate culture experiment.The results showed that the colonies in the selenium-added group spread faster around the inoculation point,and selenium addition could effectively inhibit the aging of Cordyceps militaris.The microscopic characteristics of the colonies were observed by electron microscopy.The results showed that the number of conidia was higher than that of the basic group and the density was more concentrated.Through the determination of active ingredients,it was determined that selenium supplementation promoted the production of metabolites,total sugar increased by 46.7%,cordycepin increased by 46.7%,cordycepic acid increased by 23.4%,adenosine increased by 33.3%,and production of metabolites such as organic acids and thiols Significantly increased.The crude polysaccharides were extracted from the basic group and the selenium-added group by the water extraction and alcohol precipitation method,and the yields were 1.16%and 1.73%,respectively.Two pure polysaccharides were named as CMP-Ⅱ and SeCMP-Ⅱ by Sephadex G-100 column chromatography.The total sugar contents of CMP-Ⅱ and SeCMP-Ⅱ were 86.65%and 88.80%,respectively,determined by phenol-sulfuric acid method.The weight average molecular weights of CMP-Ⅱ and SeCMP-Ⅱ were 1.936x103 kDa and 2.021×103 kDa respectively by high performance liquid chromatography(HPLC).The structure was characterized by infrared spectroscopy.It was presumed that SeCMP-Ⅱ contained selenite.Characteristic absorption peak.The structure of crude polysaccharide was analyzed by CMP-and SeCMP-Ⅱ using polarimeter,nuclear magnetic and electron microscopy.The results showed that selenium addition could affect the polysaccharide structure of Cordyeeps militaris.Three kinds of antioxidant enzymes of catalase(CAT),total superoxide dismutase(SOD)and glutathione peroxidase(GSH-PX)in the mycelium of the basic group and the selenium-added group were determined by the termination reaction method.And the activities of three kinds of polysaccharides,such as phosphoglucose mutase(PGM),UDP-glucose pyrophosphorylase(UGP)and phosphoglucose isomerase(PGI),showed that the enzyme activity and organism were added to the selenium group.Both the amount and the yield of polysaccharides increased significantly.qRT-PCR was used to detect the expression levels of cat,sodf shp.xg,pgm,pgi and ugp encoding CAT,SOD,GSH-PX,PGM,UGP and PGI.The results showed that:selenium plus three The expression of key antioxidant enzyme gene was the most important,and the effect on sod was the highest.The expression level was 1.945 times of the control group,and the expression of cat was 0.758 times of the control group.The expression level of the three polysaccharides was increased by selenium.All of them had an effect,and the expression level of pgm was the highest,and the expression level was 1.940 times of the control group. |
