Optimization of Liquid-state Fermentation for Thermophilic Protease Production by Bacillus thuringiensis FS140

Statistical methods were used to optimize the fermentation conditions for thermophilic protease production by Bacillus thuringiensis FS140.A Plackett-Burman design was used to select 3 important factors from 8 impact factors which affected protease fermentation.They were bean cake meal,yeast powder and glucose in culture medium.The optimum components obtained by the response surface methodology(RSM)were bean cake meal 1.8%,yeast powder 0.36% and glucose 0.14%,respectively.After the optimization,the yield of thermophilic protease increased markedly compared with the initial and reached 837.71 U/mL,of which only 1.34% differed from the forecast by RSM.After the optimization of fermentation conditions including fermentation temperature,initial pH,loading volume of medium and inoculation volume,the protease production reached 918.91 U/mL.Fig 2,Tab 5,Ref 14