Medium optimization for spore production of marine Bacillus subtilis HS-A38 by response surface methodology

Using shaking-flask fermentation in the laboratory,glucose and ZnSO4 affecting spore production of marine Bacillus subtilis HS-A38 were determined by the design of Plackett-Burman.The region of the fermentation conditions was approached through the path of steepest ascent.Subsequently,the concentration of those important factors were optimized by Central Composite Design(CCD) and response surface analysis by Design expert 7.13.The concentration of ingredients is as glucose 8.49 g/L,soybean powder 12.0 g/L,urea 0.625 g/L,yeast extract 4.0 g/L,K2HPO4 4.0 g/L,ZnSO4 0.053 g/L.The colony-forming units per milliliter(cfu/mL) were improved from 7.22×108 to 1.64×109 after medium optimization,and the yield of cfu/mL is increased by more than one time.This study suggests that the spore concentration can be improved by the experimental designs.