COMPARATIVE-ANALYSIS OF THE 16S TO 23S RIBOSOMAL INTERGENIC SPACER SEQUENCES OF BACILLUS-THURINGIENSIS STRAINS AND SUBSPECIES AND OF CLOSELY-RELATED SPECIES

Bacillus thuringiensis spacer regions between the 16S and 23S rRNAs we re amplified with conserved primers, designated 19-mer and 23-mer prim ers. A spacer region of 144 bp was determined for all of 6 B. thuringi ensis strains, 7 B. thuringiensis subspecies, and 11 B. thuringiensis field isolates, as well as for the closely related species Bacillus ce reus and Bacillus anthracis. Computer analysis and alignment of nucleo tide sequences identified three mutations and one deletion in the inte rgenic spacer region (ISR) of B. thuringiensis subsp. kurstaki HD-1 wh en compared with ISR sequences from other subspecies. The same differe nces were identified between the ISR of B. thuringiensis strains and t he ISR of B. cereus and B. anthracis. These minor differences do not s eem to be sufficient to allow the design of a species-specific oligonu cleotide probe.