A novel method for the production of a selenium-enriched yeast /

Selenium (Se) is an essential element. Supplementation of Se as yeast-Se in animal and human diets has been proven to have beneficial health effects. The goal of this study was to add a maximum amount of Se in yeast metabolism in order to optimize its incorporation in amino acids. A bakery yeast strain of Saccharomyces cerevisiae (S. cerevisiae) was studied for its tolerance to Se when the latter was incorporated at different levels. Fermentations were run at 27°C for 8 h and 24 h. The maximum Se incorporation was achieved when 12.6 mmol of Se, as sodium selenite salt, was added to the culture medium and fermented for 24 h. A final Se concentration of 1550 +/- 35 mug/g yeast was obtained by this treatment.Different yeast strains of S. cerevisiae were also studied for their capacity to incorporate Se. Five yeast strains of wine and four yeast strains of beer were fermented for 24 h and tested for their capacity to incorporate Se. The amount of 12.6 mmol Se was added in the growth medium. A maximum of 642.6 +/- 3.6 mug Se/g yeast was found to be incorporated in Uvaferm BC wine strain. Uvaferm windsor of beer strain was able to incorporate a maximum of 826.8 +/- 10.4 mug Se/g yeast. These yeast strains could be used as alternatives for Se supplementation.Se speciation was carried out on the bakery yeast strain containing 1550 +/- 35 mug Se/g yeast, using Fast Phase Liquid Chromatography (FPLC) and amino acid analysis. Out of 1550 +/- 35 mug Se/g yeast, 57.5% Se was present as selenoaminoacids. The yeast extract contained 147 +/- 14 mug/g of SeCys, 248 +/- 13 mug/g of SeCyst and 295 +/- 17 mug/g of SeMet. Yeast cell walls contained 65 +/- 8 mug/g of SeMet; 69 +/- 5 mug/g of SeCyst and 67 +/- 9 mug/g of SeCys. These selenoaminoacids are known for their beneficial health effects. The produced Se-enriched bakery yeast could be used, after evaluated to be toxicologically safe, as an efficient dietary supplement