Recombinant Escherichia coli strains harboring pAG1, pAG2, pKBB100, and pKBB101 were cloned by using antiserum constructed against 130-kDa crystal protein antigen of Bacillus thuringiensis serovar japonensis strain Buibui. DNAs in the recombinant strains hybridized to the 26-base oligonucleotide probe corresponding to N-terminal amino acids of the 130-kDa crystal protein of strain Buibui. Cultures of the recombinant strains were toxic to larvae of the cupreous chafer, Anomala cuprea. Furthermore, the production of the 130-kDa polypeptide was demonstrated in the cells harboring pAG1 and pAG2 by immunoblot analysis with antiserum against the 130-kDa crystal protein. Southern hybridization analysis showed that the 130-kDa crystal protein gene is located on the chromosomal DNA of strain Buibui. On the other hand, DNA probes derived from cryIA(a) and cryIIIA genes did not hybridize to the DNA of strain Buibui.