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苏云金芽孢杆菌BRC-LLP29为新型高效杀蚊菌株,应用快速有效的数学统计方法对其杀蚊毒力的发酵培养进行优化.通过单因素筛选确定最佳碳源为葡萄糖、麦芽糖、可溶性淀粉,氮源为typetone、大豆蛋白胨、干酪素;最佳金属离子为Mg~(2+)、Al~(3+).采用二水平Placlkett-Burman设计对影响毒力的8因素进行显著性筛选,获得培养基成分中3个重要影响因子:葡萄糖、干酪素和Al_2(SO_4)_3;运用爬坡路径法对这3种因子进行试验,获得3种重要因子的最适浓度范围;通过响应面分析法得到3个重要因子的交互作用和最佳条件,确定BRC-LLP29菌株最佳毒力水平的发酵培养基为:葡萄糖19.8g/L、干酪素28.4g/L、Al_2(SO_4)_31.2g/L、MgSO_4 2g/L、K_2HPO_4 3g/L、CaCO_3 0.5g/L,优化后毒力水平达到致死率61.11%,与响应面数学模型的预测值只有5.91%的误差.发酵条件优化结果表明:发酵温度为31°,发酵初始pH为7.0,摇瓶装量为40mL/250mL三角瓶,每瓶的接种量为3.5%,发酵72h,对致倦库蚊最终致死率达到最高为83.33%.
Bacillus thuringiensis BRC-LLP29 is a new type of highly effective mosquito-killing mosquito strain, and its rapid and effective mathematical statistical method is used to optimize the fermentation culture of mosquito-killing virulence.Under single factor screening, the optimal carbon source is glucose, maltose, soluble starch, The source was typetone, soy peptone and casein, and the best metal ions were Mg ~ (2 +) and Al ~ (3+). Eight factors influencing virulence were screened by two levels of Placlkett-Burman design, Three important influencing factors were glucose, casein and Al_2 (SO_4) _3. The climbing path method was used to test these three factors to get the optimum concentration range of three important factors. The response surface analysis The interaction and optimal conditions of three important factors, the optimal fermentation medium for the determination of BRC-LLP29 strain was 19.8g / L glucose, 28.4g / L casein, 31.2g / L Al_2 (SO_4) , MgSO_4 2g / L, K_2HPO_4 3g / L, CaCO_3 0.5g / L, the virulence of the optimized virulence reached 61.11%, which is only 5.91% of the expected value of the response surface mathematical model.Experimental results of fermentation conditions showed that fermentation temperature 31 °, the initial fermentation pH 7.0, shake flask loading 40mL / 250mL flask, bottle inoculum size is 3.5%, the fermentation 72h, Culex quinquefasciatus to the final highest death rate was 83.33%.