Abstract: Cry toxins produced by Bacillus thuringiensis (Bt) could provide a valuable resource for efficient pest control. But insect midgut proteases could be a limiting step of Cry toxicity in different insect species. This article analyzed several different strategies of improving toxicity against a specific target, including domain Ⅲ swapping, domain Ⅱ and domain Ⅲ mutations and other mutations in Cry toxins. Furthermore, this article also expounded the phage display to optimize toxin, which improved the insecticidal toxicity against pests that show no susceptibility to the parental Cry toxins. The paper was expected to provide reference for molecular modification and application of Cry toxin.

Key words: Bacillus thuringiensis, cry toxin, evolution, molecular modification

摘要： 苏云金芽胞杆菌（Bacillus thuringiensis,Bt）产生的Cry毒素为防治害虫提供了一种宝贵的资源。但昆虫中肠蛋白酶的活化作用在不同的昆虫中对Cry毒素的杀虫活性有限制性。分析了几种不同的策略来增加Cry毒素对靶标昆虫的毒性，包括结构域Ⅲ交换、结构域Ⅱ和结构域Ⅲ的突变以及其他突变。此外，还详细阐述了噬菌体展示技术进行毒素优化的方法，毒素优化能够增加Cry毒素对亲本Cry毒素敏感度较低的害虫的杀虫活性，以期为Cry毒素的分子改造和应用提供参考。

关键词: 苏云金芽胞杆菌, Cry毒素, 进化, 分子改造