Abstract:

Plackett-Burman design was used to evaluate the importance of fermentation medium factors of Bacillus subtilis BSD-2 affecting the inhibitory zone diameter of produced antibacterial peptides. Subsequently, 7 steepest ascent experiments involving 3 most important factors (i.e., peptone, starch and soybean meal) were conducted for approaching their optimal response region. Finally, the optimal fermentation medium formula was obtained by optimizing the most important factors using central composite design combined with response surface methodology. Results indicated that the optimal fermentation medium formula consisted of 14.29 g/L peptone, 14.07 g/L amylum, 6.49 g/L soybean power, 2.0 g/L CaCO3 and 1.0 g/L MgSO4. There was a 1.77-fold increase in the yield of antibacterial peptides obtained using the optimal fermentation medium, compared with that before optimization.

Key words: Bacillus subtilis, response surface methodology, Minitab software, medium optimization, antibacterial peptide