CLONING AND EXPRESSION OF CryIVD GENE OF INSECTICIDAL CRYSTAL PROTEIN OF BACILLUS THURINGIENSIS IN THE ACRYSTALLIFEROUS STRAIN

Abstract The plasmid pGEMl, carrying CryIV D, CytA and 20-kDa protein genes, was extracted and digested with Hind II /BamH I. A 5.4 kb fragment containing Cry IV D and 20-kDa protein gene was purified and ligated to an E. coli TG1. The recombinant plasmid was analyzed by restriction map and Southern blotting to determine the correct insert. Then the recombinant was transferred into Bacillus thuringiensis acrystalliferous mutant Bti. IPS. 78/11 by electroporation. The clones with strong expressiveness were obtained. The engineered strains express 72-kDa and 20-kDa proteins and form irregular hexagon paras-pore crystal. One strain bioassayed is very toxic to Culex fatigans larvae with LC₅₀ of 0. 53 μg/ml.