Optimization of Fermentation Process of Bacillus amyloliquefaciens Lx-11

The Plackett-Burman experiments and response surface methodology were adopted to optimize the liquid fermentation medium and conditions of the biocontrol agent of Bacillus amyloliquefaciens Lx-11.According to the evaluation by the response surface model established in this study,the optimum mass concentrations of the three components,corn starch,soyean powder and yeast extract,in fermentation medium were 11.2 g?L?1,14.6 g?L?1 and 0.62 g?L?1,respectively.The fermentation condition determination tests indicated that temperature,filling volume of shaking flask and inoculum volume were the major factors affecting Lx-11 yield.The optimized fermentation conditions were 30.84 °C,inoculum volume 1.52% and the filling volume 59.68 mL in 250 mL shaking flask for 48 h at 150 r?min-1,and initial pH 7.0.Under the conditions spore production was up to 3.75×109 cfu?mL?1 and the width of antibacterial activity was 8.2 mm.Fermentation experiments with shake flasks verified that there was no statistical difference between real and forcasted yields.