Evaluation of low molecular weight RNA profiles and ribotyping to differentiate some Bacillus species

Low molecular weight (LMW) RNA profiles and restriction fragment length polymorphisms (RFLPs) based on probing for ribosomal DNA sequences were evaluated as complementary techniques to differentiate between and identify common species of Bacillus. The collection included type strains from ATCC, strains from various laboratories, and natural isolates of B, mycoides. Neither LMW RNA profiles nor RFLP analysis alone were able to differentiate between ail species of Bacillus examined in this study. The LMW RNA profiles of the species in the B, cereus complex (B. cereus, B. mycoides, and B. thuringiensis) were indistinguishable; so were the B. subtilis and B. amyloliquefaciens profiles. The RFLPs of the B. cereus complex, B. amyloliquefaciens, and B. pumilus were apparently identical; so were those of B. subtilis and B. licheniformis. Bacillus brevis, B. sphaericus, B. megaterium and B, circulans had distinct LMW RNA profiles and RFLPs. The LMW RNA profiles of strains of the B, cereus complex were found to be affected by the presence of Mn+2, Mg+2, and Ca+2 in the growth medium and possibly the physiological state of the cells when the RNA was extracted. The combination of the two techniques was able to discriminate between all species except the B. cereus complex.