Selenium has been recognized as an essential nutrient for human health; however, the gap between toxic and essential levels of selenium is narrow. The recommended daily selenium dose for adult humans ranges from 50-100 μg and it should not exceed 400 μg. The capability of baker's yeast to bind with Se+4 ions which are present in the yeast-culture media has provided an opportunity to obtain natural bioplexes of this microelement. The influence of incubation conditions on efficiency of selenium enrichment in baker’s yeast was studied. The study process factors were as follow: factor 1: glucose concentration (0.055, 0.166, 0.277 mol dm-3); factor 2: incubation temperature (25, 30, and 35°C); factor 3: selenium concentration (1, 4, 7 10-4 mol dm-3). The yeast cell enrichment with selenium was conducted for 24 hrs. Data were analysed by using the Pearson correlation coefficient. The selenium bioaccumulation values ranged from 141.67 to 1136.69 mg kg-1 of dried baker's yeast. It was shown that the content of total selenium (r = 0.99, p = 0.0001) and organic selenium (r = 0.99, p = 0.0001) in yeast biomass correlated positively with its concentration in the culture medium, while selenium concentration in the medium had significantly negative correlation with yeast biomass (r = -0.92, p = 0.0001). The Pearson correlation coefficient showed a significant correlation between glucose concentration and biomass yield (r = 0.27, p = 0.048). Temperature (r = 0.44, p = 0.002) and the concentration of glucose in culture medium (r = 0.80, p = 0.0001) correlated positively with total process efficiency. The highest amount of selenium (1136.69 mg kg-1) incorporation was obtained in variant 8: with sugar concentration of 0.277 mol dm-3 and selenium concentration of 7 10-4 mol dm-3 in the medium, at the temperature of 35°C.

22.4.2016