Abstract: In this paper, Lactobacillus bulgaricus (LB) was cultured in the medium with Se. The inorganic state trace element Se was changed into the organic state trace element through bio-transformation. The effect of different conditions on enrichment of trace element Se by LB was assessed with the orthogonal design of L9(34). The results showed that Na2SeO3 concentration in the medium was the main influence factor; the culture temperature, the culture time and the inoculation volume were the secondary influence factors. The optimal enriching conditions of Se by LB were as follows: Na2SeO3 concentration, 90μg/ml; the culture temperature, 37℃; the culture time, 60h; and the inoculation volume, 8%. The amount of organic form of Se was above 80%.

Key words: Lactobacillus bulgaricus, trace element Se, enriching conditions