Study On Selenium-enrichment By Saccharomyces Cerevisiae

Selenium is an essential trace element in human nutrition and selenium deficiency or excess has been implicated in several diseases. To date, fourteen selenoproteins have been identified in animals and the known biological functions of Se include defense against oxidative stress, regulation of thyroid hormone action, and regulation of the redox status of vitamin C. Selenium is also correlated with many disease's development and advances, especially cardiopathy, diabetes, tumour and AIDS. Selenium deficiency is a contributing cause of Keshan disease. Selenium deficiency is also observed in patients with HIV/AIDS. So selenium has crucial roles in human health.The FAO/WHO has set the recommended daily allowance for Se: 26μg/d and 34μg/d for women and men respectively. Dietary selenium intakes in low soil Se areas of China is 3-11μg/d。Selenium is always very low in natural food, and inorganic Se is not able to be used in food because of its higher toxicity, so it is important to research and develop kinds of Se-enriched foods by microorganism for health.Saccharomyces cerevisiae was used for Studying the ability of enriching Se in microorganism, the majority of work as follows:(1) Screened a L strain which has higher ability of enriching Se from 7 strains in our lab as experimental strain.(2)Breeded a strain named L-11-7-2 with higher biomass, higher Se content and higher Semet content after adapted cultivation, DES domestication and screening from culture contained Se and culture contained ethionine. Compared to L-11-7-2 strain, the Se content and the biomass of L strain were enhanced to 2452μg/g and 7.9 g /L respectively. Using GC-MS to measure the content of Semet, the result shows that the content of Semet was 1650μg/g which was nearly 67.3% of the total Se.(3) After fed-batch cultivating, the content of Se in S. cerevisiae was up to 3351μg/g. In the same time, the microorganism assimilated 2.29g Se, and the absorptivity of Se was 95.4%. The content of Semet was 2157μg/g, about 64.36% of the total Se.