Optimization of Brevibacillin Fermentation Medium with Brevibacillus laterosporus by Response Surface Methodology

The fermentation medium of brevibacillin by Brevibacillus laterosporus was optimized. Six main factors which affected brevibacillin production were evaluated by Placket-burman design. Three significant factors, sucrose, beef extract and Mg²⁺, were selected and the optimal area of the response surface was determined by the steepest climbing experimental; the optimal medium components were obtained by using a three-factor and three-level Box-Behnken experiment. The optimal medium components for B. laterosporus producing brevibacillin were: Sucrose 28.65 g/L, beef extract 17.04 g/L, Mg²⁺13.01 g/L, tryptone 10 g/L, yeast extract 5 g/L, NaCl 10 g/L. Under this optimum condition the yield of brevibacillin was 457.87±5.12 µg/mL, which was 34.6% higher that before optimization, and it was very close to the maximum value 462.94 µg/mL predicted by the theory.