| Selenium(Se)is an essential trace element of biological organisms.Selenium can promote the growth and detoxification of heavy metals and other biological functions.However,the distribution of selenium in China is uneven,which leads to the existence of selenium deficiency in many people.Inorganic selenium is low in toxicity and low in biological activity,and the absorption effect of the human body is not ideal.The absorption rate of organic selenium is obviously higher than that of inorganic selenium,and its toxicity is very small.Therefore,for selenium supplement,it has a very good effect.In this study,organic selenium was synthesized by microbial transformation,and Saccharomyces cerevisiae and Yuanbao Ganoderma lucidum were used as the carrier of selenium enrichment to prepare selenium enriched yeast and selenium rich Ganoderma.The selenium content reached the national standard,which could be used for reference for the later industrialization of selenium rich food.In this paper,the liquid fermentation conditions of Yuanbao Ganoderma lucidum,the selenium enrichment of Saccharomyces cerevisiae and the supplementation time of selenium in the selenium rich culture of Yuanbao Ganoderma lucidum were studied,and the concentration of sodium selenite was determined.The contents of organic selenium and total selenium in two strains were measured,the extraction process of selenium polysaccharide and selenoprotein was studied,the content of selenoprotein and selenium polysaccharide was determined,and the antioxidant properties of selenoprotein and selenium polysaccharide were studied.First,a strain of YBF-2 was selected to determine the content of polysaccharide in the cell and the resistance to selenium.The Saccharomyces cerevisiae strain NY-1 was obtained on the plate containing sodium selenite by gradient culture.The optimum medium group for liquid fermentation of Yuanbao Ganoderma lucidum YBF-2 was determined by the two parameters of intracellular and external polysaccharides.The optimum medium group for liquid fermentation of Yuanbao Ganoderma lucidum YBF-2 was as follows:glucose 20 g/L,yeast dipping 10 g/L,KH2P04 1 g/L,MgS04 0.5 g/L,VBi 50 mg/L.Single factor test was used to determine the optimum culture conditions for shaking bottle fermentation of Yuanbao Ganoderma lucidum at 28?,pH 6.5,5%inoculation quantity and 220 rpm respectively.Secondly,the extraction process of selenium polysaccharide and selenoprotein from Yuanbao Ganoderma lucidum YBF-2 were optimized.The optimum extraction condition of extracting selenium polysaccharide was:material to solution ratio of 1:60,The optimum temperature is 100 ?,the best time is 2 h,the best ethanol content is 80%,and the best number is 3 times.The extraction process of selenoprotein from selenium rich Yuanbao Ganoderma lucidum YBF-2 is:the concentration of sodium hydroxide solution of 0.1 mol/L,the ratio of material to liquid of 1:20,The best temperature is 60 ?,the best time is 2 h,the best number is 3 times.At the same time,the isoelectric point of selenoprotein is 4.Then,in Saccharomyces cerevisiae NY-1 culture for selenium biotransformation,the concentration of sodium selenite was determined to be 20 mg/L and the addition time was at 8 h.In Yuanbao Ganoderma lucidum YBF-2 culture for selenium biotransformation,the concentration of sodium selenite was 12 mg/L and the addition time was at 16 h.The total selenium content of selenium enriched Saccharomyces cerevisiae NY-1 was 1540.3 mg/kg and the content of organic selenium was 1496.8 mg/kg.The percentage of organic selenium was 97.2%.The total selenium content of selenium enriched Yuanbao Ganoderma lucidum YBF-2 was 338 mg/kg,and the content of organic selenium was 331.42 mg/kg.Organic selenium accounted for 98.05%of total selenium.All reached the national standard of selenium enriched yeast and selenium enriched edible fungus powder.The detection of scavenging capacity of DPPH and superoxide radical proved that Se polysaccharide and selenoprotein to have good antioxidant effect. |
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