INORGANIC SELENIUM UPTAKE BY Lactobacillus ssp.

Selenium is an essential micronutrient to human metabolism and it has been demonstrated that it has a marked antioxidant effect. In its inorganic form, selenium can be potentially toxic for human health, while its availability increases in its organic form and its toxicity declines. Inorganic selenium is incorporated in some lactic acid bacteria, which are commonly used as starter in fermented dairy products. The aim of this research was to determine and quantify the capacity of selenium incorporation in Lactobacillus ssp. metabolism, by ICP. Culture media were enriched with Na2SeO3 in order to determine such capacity. Four lactic acid bacteria were used and their tolerance to selenium was determined by adding Na2SeO3 to growth medium. Lactobacillus rhamnosus GG presented the highest tolerance (198 mg/L). Lactobacillus delbrueckii subsp. bulgaricus NCFB2772 showed the lowest assimilation of inorganic selenium (9.14%) while L. helveticus IUAMI- 70129 had the highest (76.50%) despite being the microorganism which displayed the least tolerance (43 mg/L). On the other hand, Lactobacillus jhonsonii showed the highest concentration of selenium in terms of generated biomass weight (0.91 g/mg). Finally, all bacteria under study assimilated inorganic selenium. Therefore, they could be used as starter cultures or as functional ingredients, for elaboration of foods enriched with selenium. Keywords: selenium, lactic acid bacteria, selenoproteins, starter, fermented dairy products