In this study, we rapidly identified Bacillus thuringiensis 4.0718 strain that harbored the known cry1 and cry2 type genes by a PCR strategy. Three pairs of universal oligonucleotide primers were designed to detect all known cry1, cry2 and cry3 type gene sequences. Then the DNA of the positive strain 4.0718 was probed with a set of specific primers. One feacture of this screening method was that each gene was expected to produce a PCR product having a precise molecular weight. PCR products having different sizes probably represented the gene was a potentially novel gene. Differentiations among these genes was determined on the basis of the electrophoresis patterns of PCR products. Finally, five cry1 type genes (cry1Aa, cry1Ab, cry1Ac, cry1Cb, a novel cry4.5 type genes) and one cry2Ac type gene had been detected from Bacillus thuringiensis 4.0718 strain.
