EVALUATION OF LOW-MOLECULAR-WEIGHT RNA PROFILES AND RIBOTYPING TO DIFFERENTIATE SOME BACILLUS SPECIES

Low molecular weight (LMW) RNA profiles and restriction fragment lengt h polymorphisms (RFLPs) based on probing for ribosomal DNA sequences w ere evaluated as complementary techniques to differentiate between and identify common species of Bacillus. The collection included type str ains from ATCC, strains from various laboratories, and natural isolate s of B, mycoides. Neither LMW RNA profiles nor RFLP analysis alone wer e able to differentiate between ail species of Bacillus examined in th is 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 a pparently identical; so were those of B. subtilis and B. licheniformis . Bacillus brevis, B. sphaericus, B. megaterium and B, circulans had d istinct 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 th e B. cereus complex.