DISCRIMINATION AMONG THE BACILLUS-CEREUS GROUP, IN COMPARISON TO BACILLUS-SUBTILIS, BY STRUCTURAL CARBOHYDRATE PROFILES AND RIBOSOMAL-RNA SPACER REGION PCR

The B. cereus group (B. anthracis, B. thuringiensis and B. cereus) and B. subtilis were physiologically, molecularly and chemically characterized. Within the B. cereus group, strains grew anaerobically and were not lysozyme susceptible. B. anthracis strains were non-hemolytic unlike B. cereus or B. thuringiensis. Only B. thuringiensis produced parasporal bodies. The 16S/23S rRNA spacer region was amplified giving 3 major produces. The PCR products found in strains of B. subtilis were approximately 270, 400, and 430 nucleotides, with the corresponding bands in the B. cereus group at 250, 430, and 480. These patterns allowed B. subtilis to be differentiated from the other 3 species. Using gas chromatography-mass spectrometry, sugar profiles of vegetative cells were indistinguishable for B. cereus and B. thuringiensis. B. anthracis contained high levels of galactose which generally distinguished it from B. cereus/B. thuringiensis, while B. subtilis was distinguished from the B. cereus group by low mannosamine levels. Spore profiles differed from vegetative profiles in all 4 species. Like vegetative profiles, spore profiles were distinctive for B. cereus/B. thuringiensis, B. anthracis, and B. subtilis. B. cereus and B. thuringiensis spores both contained rhamnose, fucose, 2-O-methyl rhamnose and 3-O-methyl rhamnose, unlike B. anthracis spores which contained only rhamnose and 3-O-methyl rhamnose. B. subtilis strains were heterogeneous with some resembling B. anthracis and others B. cereus/B. thuringiensis, although B. subtilis strains typically contained quinovose, The B. cereus group can be easily distinguished from B. subtilis, however, differentiation within this group has always been problematic. Using carbohydrate profiling, B. anthracis is readily distinguished from B. cereus (B. thuringiensis. Additionally, changes in carbohydrate composition between vegetative cells and spores occurs in the B. cereus group and B. subtilis.