24 h-old cultures of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisco), yeast (Saccharomyces cerevisiae) and mixed population of these strains grown on MRS medium with various doses of SeO₂ were investigated. Different correlation between the concentration of inorganic selenium in the medium and biomass was shown for the strains. Among Lactobacillus the best selenium accumulation was observed for Lactobacillus plantarum: 77, 244, 401 and 22200μg Se/g dry weight for 1, 5, 10 and 20 μg Se/cm³ of the medium, respectively. For the yeast, at the above given selenium concentrations in the culture medium, the following selenium concentrations were obtained in the biomass: 12, 113, 154 and 364μg Se/g dry weight, respectively. For all the selenium doses a negative effect of SeO₂ on the growth parameters of both physiological groups was observed. Additionally, at the selenium content in the medium exceeding 10 μg Se/cm³ , red colour of biomass was observed as caused by elemental selenium concentration. Associating bacteria strains with yeast brought about a symbiotic effect. The amount of accumulated selenium was considerably greater (281 μg Se/g dry weight at 5 μg Se/cm³ in the medium) than for single strains and growth parameters of bacteria were also improved.