Bacteria/yeast and plant biomass enriched in Se via bioconversion process as a source of Se supplementation in food

Mono and mixed populations of lactic acid bacteria of Lactobacillus species (Lb. plantarum, Lb. sanfrancisco, Lb. brevis) and the yeast Saccharomyces cerevisiae were tested for their ability to accumulate Se from the culture medium containing different inorganic Se sources (SeO2, Na2SeO3, Na2SeO4). A high correlation between Se concentration in culture medium and Se content in biomass was observed. The highest amounts of Se in Lactobacillus species was observed with Lb. plantarum and the lowest one with Lb. sanfrancisco. Under the same conditions yeast accumulated considerable lower amounts of selenium. In all tested strains at concentrations higher than 10 mug Se/ml in the medium, there was an abrupt increase in Se content in the biomass with associated brick red color of free amorphous selenium deposit. At all Se levels a negative effect on growth parameters was observed. However, in a mixed population a stimulating effect on selenium accumulation and the growth parameters has been seen. For all strains selenite was the best and selenate the worst source of selenium. Plant seeds and grains were germinated during 3-5 days on culture plates rinsed with water containing different concentrations (1-30 mug Se/ml) of inorganic selenium. Screening tests have shown different Se accumulation for individual plants. Similar accumulations of Se with tap, mineral and distilled water and with Se inorganic source of +4 or +6 oxidation state were seen. A. one-stage fermentation process of bread production was used to test an effect of Se-enriched plant and bacteria-yeast biomass on the fermentation process. Technological parameters and bread quality of regular and Se-enriched bread (with 70-80 mug Se/250g) were comparable.