Optimization of Bacillus thuringiensis A322 Strain Fermentation Medium and Cultural Conditions

Key words: 
• Bacillus thuringiensis /
• medium /
• fermentation condition /
• optimization

Abstract: Bacillus thuringiensis Berliner strain A322 with higher activity against Helicoverpa armigera Hubner screened indoor was cultured on media through single-factor and orthogonal experiment to optimize cultural medium based on the optimization standard of OD₆₀₀ of the fermented liquid of B. thuringiensis at the late logarithmic phase. The optimum medium is 0. 5% soybean meal,0. 5% yeast extract,0. 5% glucose,0. 5% tryptone,0. 2% calcium carbonate,0. 1% potassium dihydrogen phosphate,and 0. 1% magnesium sulfate. The major factors in laboratory shake flask liquid fermentation,such as initial p H,temperature,speed,etc were determined. The optimum cultural conditions are found to be incubation time 20 h,p H7. 5,fermentation temperatures 30 ℃,speed 200 r·min^-1,inoculum size 3%,and medium volume 35 m L in a 250 m L flask. The OD₆₀₀ value of the bacterial growth was increased by 21. 9% after optimization of the cultural conditions.