[Characterization of insecticidal crystal proteins of Bacillus thuringiensis subsp. chinensis CT-43]

Bacillus thuringiensis subsp. chinensis CT-43, no flagellum, produces various shaped parasporal crystals, which consist of 140000, 130000, and 65000 proteins. Based on two kinds of mutant, 140000 and 130000 crystal protein individually forms bipyramidal crystal and the 65000 protein forms cubidal crystal, and that the 140000 and 130000 protein is activated by trypsin into 55000 and 66000 proteins and 60000 protein, respectively. Bioassay were conducted to 3rd instar Plutella xylostella larvae with crystals, soluble crystal proteins, and activated crystal proteins, respectively, and it indicated that high toxic mutants can be obtained by curing low toxic crystal genes, and that the toxicity of crystals can be improved 16.3 to 58.4 times after solubilization.