Abstract: To obtain selenium-enriched Candida utilis to prepare feed additives to feed livestock and poultry, and obtain selenium-enriched agricultural products, C. utilis was used as the starting strain to optimize the shake flask culture conditions, including the volume of shake flask, the inoculation volume, the amount and time of sodium selenite addition, and the initial pH of the culture fluid. Then the L₉（3⁴）orthogonal test was done to obtain the optimum fermentation process when liquid volume was 35 mL, the initial pH was 6.5, and the inoculation volume was 8%. When sodium selenite was added at 12 h at 15 μg/mL, the total organic selenium content in the final fermentation broth was the highest at 9 792.732 μg/L. The content was 1 400.362 μg/mL. The fermentor was then cultivated to obtain high biomass selenium-rich C. utilis to make feed additives. Through feed culture, the biomass was 19.128 g/L, and the total organic selenium in the fermentation broth was 10 089 μg/L.

Key words: Candida utilis, selenium enrichment, fermentation tank, optimization of condition