Bt毒蛋白基因重组大肠杆菌的杀虫活性研究

Toxicity of Bt Toxic Protein Expressed by cry1Aa Cloned in Escherichia coli

本文对Bt毒蛋白基因(cry1Aa)重组大肠杆菌(ECE52)的发酵条件及杀虫活性进行了研究,结果表明该菌在37℃下培养或发酵8～12h较为合适.经超声波破碎的菌体对家蚕4龄幼虫有较强的毒性,用62.5×10-6g/mL的菌体稀释液处理过的桑叶饲喂4龄家蚕幼虫12h,96h内死亡率达100%.当浓度分别为125×10-6g/mL、250×10-6g/mL、500×10-6g/mL时,供试幼虫在72h,48h,24h内全部死亡.饲喂后24h,48h,72h的LC50值分别为0.101×10-3g/mL、0.045×10-3g/mL、0.028×10-3g/mL.

The cultural characteristics and toxicity of Bt cry1Aa gene cloned in Escherichia coli (ECE52) were studied. The results indicated that the optimal cultural condition for this engineered bacterium was (8～12h) at 37C.Toxicity tests showed that the crystal protein expressed by ECE52 possessed high toxicity to the fourth instars larvae of silkworm. The mortality of larvae was 100% in 96h when fresh leaves treated by (62.5 ×10^(-6)g/mL) ECE52 were provided as food for 12h. All tested larvae were died in 24h ,48h ,72h when higher concentration of 500 ×10^(-6)g/mL,250 ×10^(-6)g/mL,125×10^(-6)g/mL were used,respectively. The LC_(50 )value at 24h,48h,72h is 0.101×10^(-3)g/mL,0.045×10^(-3)g/mL,0.028×10^(-3)g/mL, respectively.