Preparation of elemental selenium-enriched fermented milk by newly isolated Lactobacillus brevis from kefir grains

A Lactobacillus brevis strain CGMCC No. 6683 that can survive at high selenium concentrations was isolated from kefir grains. Using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope, it was shown that L. brevis CGMCC No. 6683 reduced sodium selenite into elemental selenium. L. brevis CGMCC No. 6683 was then pre-treated with sodium selenite to prepare selenium-enriched L. brevis. To study the selenium-enriched yoghurt, selenium-enriched L. brevis was co-fermented in skimmed milk with traditional yoghurt starter culture (Streptococcus thermophilus and Lactobacillus bulgaricus). Results showed that it enhanced selenium concentration in the selenium-enriched yoghurt, and more importantly, elemental selenium was detected in the selenium-enriched yoghurt. The isolated L. brevis provides a new way of preparing a functional dairy product: elemental selenium-enriched fermented milk.