Abstract: The fermentation medium components for spore content by Bacillus amyloliquefaciens strain C101 was optimized by response surface methodology（RSM）. Firstly, three of the most significant influence factors were screened by the method of Plackett-Burman design as MnSO₄, KH₂PO₄ and（NH₄）₂SO₄. The path of steepest ascent was applied to approach the optimal region of the three significant factors. Lastly, the optimal concentration and correlations among three factors were identified by RSM. The optimal fermentation conditions were determined as followed：sucrose 20 g/L, urea 4.0 g/L, soybean meal 4.0 g/L, KNO₃ 2.0 g/L, Na₂HPO₄ 2.4 g/L, KH₂PO₄ 0.52 g/L, （NH₄）₂SO₄ 0.55 g/L, NaCl 1.0 g/L, MgSO₄·7H₂O 0.50 g/L, FeSO₄ 0.005 0 g/L, MnSO₄ 0.005 4 g/L. Under these conditions, the maximum theoretic spore number was 14.67×10⁸ /mL. After three parallel verifications, the maximum theoretic value was consistent with mean value of verification test and the spore number was increased by 188% compare to that before optimization.

Key words: Response surface methodology（RSM）, Bacillus amyloliquefaciens, Spore, Optimization