苏云金芽孢杆菌LLB19发酵培养基的优化

Optimization of Fermentation Medium for Spores Production of Bacillus thuringiensis LLB19

通过单因子实验对苏云金芽孢杆菌LLB19菌株发酵培养基碳氮源配方进行优化,确定以玉米淀粉、玉米粉为发酵培养基的碳源;以黄豆饼粉、酵母粉作为发酵培养基的氮源.采用Plackett-Burman设计,SAS软件分析该菌株的发酵培养基配方,确定了玉米淀粉、黄豆饼粉、酵母粉为影响LLB19菌株芽孢含量的3种重要因子.运用爬坡路径法对这3种因子进行实验,获得这3种重要因子的最适质量浓度范围.通过响应面分析法,得出3种重要影响因子的交互作用及最佳条件.确定LLB19菌株产芽孢最佳发酵培养基为:玉米淀粉20.0 g/L,黄豆饼粉26.7 g/L,酵母粉5.5 g/L,K2HPO40.3 g/L,MgSO4.7H2O 0.2 g/L,CaCO30.4 g/L,ZnSO40.2 g/L.最佳发酵培养基芽孢数为4.250×107/mL,与初始培养基芽孢数3.410×107/mL相比提高了24.6%.

The optimization of fermentation medium for spores production by Bacillus thuringiensis LLB19 was investigated. According to single factorial experiments, corn flour and corn starch, bean cake powder and yeast powder were the most suitable carbon and nitrogen sources, respectively. Plackett-Burman design was used to optimize the fermentation medium, through SAS software analyzing revealed that corn starch, bean cake powder and yeast powder were the three prime factors affecting spores production. The path of steepest ascent experiment was adopted to approach the optimal region of the medium composition. Then the optimal combined concentration and mutual effect of three factors were optimized by response surface methodology. The results show that the best medium composition was corn starch 20.0 g/L, bean cake powder 26.7 g/L, yeast powder 5.5 g/L, K2HPO4 0.3 g/ L, MgSO4.7H2O 0. 2 g/L, CaCOa 0. 4 g/L, ZnSO4 0.2 g/L, respectively, at which spores production was 4. 250×10^7/mL increasing 24.6% compared with the 3. 410× 10^7/mL of minimal medium.