Interspecies relations between Bacillus thuringiensis strains studied by AP-PCR and sequence analysis of ribosomal operon regions

The interspecies relationships between Bacillus thuringiensis strains producing different types of delta-endotoxins were studied using a range of molecular-biological methods. Analysis of the 16S rRNA nucleotide sequence, the 16S to 23S rRNA intergenic spacer sequence, and the 5'-terminal region of 23S rRNA allowed the studied strains to be subdivided into three groups based on the pattern of nucleotide substitutions. In terms of the pattern of substitutions, the strains of the first group are similar to the B. thuringiensis type strain ATCC 10792(T), the strains of the second group are practically identical to B. anthracis and the B. cereus type strain ATCC 14579(T), whereas the third group combines strains of B. thuringiensis subsp. morrisoni with the cry2 gene and strains of B. thuringiensis subsp. tenebrionis with the cry3 gene. PCR fingerprinting with the use of six different primer systems ((GTG)(5), REP, ERIC, and DIR) confirmed the presence of three statistically relevant groups, whose structure correlated with that suggested by the analysis of ribosomal operon regions.