Abstract：Vegetative insecticidal protein (Vip) is secreted by Bacillus thuringiensis (Bt) during the period from vegetative growth to logarithmic metaphase. To obtain efficient expression condition of Vip3Aa protein, 3 main factors (concentration of isopropyl-β-d-thiogalactoside(IPTG), inducing time and inducing temperature) were screened for the optimization inducing condition of recombinant Escherichia coli BL21-pCzn1-Vip in producing the Vip3Aa by orthogonal experiment. The highest expression level of target protein could be attained with the condition of 200 μg/mL IPTG inducing for 8 h at 21 ℃. The data were analyzed by direct calculation and one-way ANOVA method. R value (resulting from direct calculation) of inducing temperature was the highest among the 3 factors, followed by the inducing time and the concentration of IPTG, wihch indicated that the inducing temperature was the most important factor to affect expression level of target protein. P value from one-way ANOVA of inducing temperature and inducing time was lower than 0.01 and 0.05, respectively, and the P value of the other factor was higher than 0.05, which were similar as the results of direct calculation. The amount of the expressed target protein at the optimal inducing condition was up to 27.6% of total protein, which was 2.3 times of the production before optimization. It can provide the basis for the Vip3Aa manufacture, in-depth theoretical research and practical application.
