Study On The Low Of Dynamic Development In Selenium Enrichment Liquid Culture By Pleurotus Geesteranus

Selenium, an essential trace element,,which plays an important role in maintaining life activities. Because of lacking in selenium resource of about70%arable land in China. How safely to develop the seleniferous food resources has become an interested research field in food science, biology, and medicine. The enrichment in seleniferous mycelium of edible fungi with submerged culture is an effective and safe way for seleniferous food production. With bioconversion of mushroom mycelia, the inorganic selenium sources can be safely metabolized into bioorganic selenium. The advantages of this bioconversion technology include not only in high efficiency and safety of organic selenium food source, but also in optimal the nutritional quality of organic selenium food source with mushroom polysaccharide, proteins and essential amino acids.Pleurotus geesteranus Singer is a rare edible fungi species with great commercial prospects. It functions especially in nutritional effects on improving immunity, anti-cancer, cancer prevention, lowering blood-lipid and cholesterol. Pleurotus geesteranus fruits or mycelia obtained from ordinary culture medium had low content of selenium. Pleurotus geesteranus stain rich in selenium obtained from previous research was used to conduct biological metabolism dynamic analysis of selenium nutritional transformation by biological metabolism enrichment of liquid culture, which provided great guidance for establishment of liquid culture system of Pleurotus geesteranus rich in selenium and development of edible fungi product rich in selenium.In this test mycelium rich in selenium was liquid cultivated in fermentor to analyze the dynamic factors of biological growth, culture environment and nutrients levels of fermentation liquid. Meanwhile a method was explored to determine the selenium content in Pleurotus geesteranus mycelium rich in selenium by spectrophotometry. And nutrients of Pleurotus geesteranus mycelium rich in selenium were analyzed and comparison of difference of mycelium nutrients between group rich in selenium and control group was conducted.Test results revealed that, Pleurotus geesteranus mycelium rich in selenium being liquid cultivated for72h in fermentor, mycelium biomass of conventional culture group (control group) and culture group rich in selenium were1.92mg/mL and1.81mg/mL respectively, showing no significant difference. Trend of dynamic change in pH and dissolved oxygen content, nutrition levels of soluble sugar and soluble protein of two groups of culture liquidwas relatively consistent.3,3-diaminobenzidine used as a complexing agent, optimal parameters of determining content of Pleurotus geesteranus mycelium rich in selection by spectrophotometry were as follows:absorption wavelength of complex420nm, addition of EDTA-2Na solution50mg/mL, dosage of complexing agent5mL, complexation pH2, colorimetric pH7, complexation reaction time50min, extraction time3min.Comparison result between nutrients content of Pleurotus geesteranus mycelium of control group and culture group rich in selenium showed that mycelium protein content of culture group rich in selenium was significantly higher than that of control group (1.18times).and the results indicated increase in nutrition metabolism of matrix selenium can help to promote synthesis of protein in mycelium. Mycelium amino acid content of control group and culture group rich in selenium were respectively6.07%and5.99%, showing significant difference. Besides, the two groups contained17amino acids and8essential amino acids and content ratio of essential amino acid and total amino acid accorded with the ideal model of reference protein proposed by FAO and WHO. Selenium content of Pleurotus geesteranus mycelium by liquid culture was up to45.37ug/g and organic selenium took up more than90%of total selenium content. The results showed that mycelium rich in selenium not only maintained nutrition and quality features, but enriched biological activity of organic selenium nutrients, which can be regarded as a bio-organic selenium complement resource of high nutritional quality and safety.In sum, liquid culture of Pleurotus geesteranus mycelium rich in selenium in fermentor was explored. Addition of3.0ug/mL sodium selenite to metabolic matrix, not only did not inhibit growth of Pleurotus geesteranus mycelium, but effective promote transformation of bio-organic selenium and generation of protein nutrition. Selenium content of Pleurotus geesteranus mycelium rich in selenium by liquid culture was up to45.37ug/g, and biotransformation rate of inorganic selenium was53.37%, fulfilling Pleurotus geesteranus mycelium rich in selenium by liquid culture safely and effectively. This test provided technical basis and technology parameters for the establishment of Pleurotus geesteranus mycelium rich in selenium by liquid culture in fermentor. Meantime, optimal parameter test for determination of mycelium selenium content by spectrophotometry provided analytical reference for organic selenium content of edible fungi. Additionally, nutrients analysis of Pleurotus geesteranus mycelium rich in selenium can improve the development of edible fungi rich in selenium.