Abstract: Response surface methodology (RSM) was used to explore medium composition and solid-state fermentation conditions for Clostridium butyricum. The amount of viable cells was used as the evaluation index. Four factors including (NH4)2SO4, MgSO4, maltose and water content as the major affecting factors of medium composition were screened from 10 factors by Plackett-Burman design. The results showed that the maximum number of viable cells of Clostridium butyricum could reach up to 76×106 CFU/g when the medium was composed of 1.5% (NH4)2SO4, 0.02% MgSO4, 0.8% maltose and 55% water content. Similarly, the fermentation conditions of Clostridium butyricum were optimized by Box-Behnken design combined with RSM. Fermentation time of 24 h, fermentation temperature of 30 ℃ and inoculation amount of 14 mL/100 g were optimum. Under these conditions, the maximum number of viable cells could reach up to 11×107 CFU/g.

Key words: Clostridium butyricum, solid-state fermentation, response surface methodology