Association of plasmid integrative J7W-1 prophage with Bacillus thuringiensis strains.

A region homologous to the genome of plasmid integrative phage J7W-1 was detected in the largest plasmid in 3 out of 22 type strains of Bacillus thuringiensis, dendrolimus (DEN), aizawai (AIZ) and indiana (IND). Phage induction by ethidium bromide observed particularly in the J7W-1 lysogen was identified in DEN and IND but not AIZ strains. The morphology of the phage induced in DEN and IND strains was identical to J7W-1, but the phage production in IND strain was lower as compared to the J7W-1 lysogen. Although the restriction analysis indicated that the prophage in DEN strain possessed a complete J7W-1 genome, modification and/or deletion had presumably occurred in AIZ and IND strains.