改造目的基因Modification of target gene

举例：Bt基因即是苏云金芽胞杆菌(Bacillusthuringiensis，简称Bt)基因，因其表达产物Bt毒蛋白杀虫效果好、安全、高效等优点而成为应用最为广泛的转杀虫基因。Bt与其它芽胞杆菌相比，一个显著特点就是不仅能够形成芽胞，同时还能产生由杀虫蛋白组成的晶体。

主要用于防治农业害虫烟草夜蛾、菜粉蝶、玉米螟、棉铃虫和森林害虫松毛虫等。

Bt制剂杀虫谱窄、安全等问题？

如何对现有Bt基因改造，表达出比天然蛋白性能更好的突变蛋白

Error-prone PCR (epPCR) is a commonly employed approach in molecular biology, especially in directed evolution, to generate libraries of DNA molecules with broad mutational spectrums. Though commonly applied to mutagenize protein coding sequences of several hundreds or thousands of basepairs, we found that commonly used protocols were not suitable for small (<100 bp) amplicons.