Phylogenetic positions of Clostridium novyi and Clostridium haemolyticum based on 16S rDNA sequences

The partial sequences (1465 bp) of the 16S rDNA of Clostridium novyi types A, B and C and Clostridium haemolyticum were determined. C, novyi types A, B and C and C. haemolyticum clustered with Clostridium botulinum types C an d D. Moreover, the 16S rDNA sequences of C, novyi type B strains and C, hae molyticum strains were completely identical; they differed by 1 bp (level o f similarity > 99.9%) from that of C, novyi type C, they were 98.7% homolog ous to that of C, novyi type A (relative positions 28-1520 of the Escherich ia coli 16S rDNA sequence) and they exhibited a higher similarity to the 16 S rDNA sequence of C. botulinum types D and C than to that of C. novyi type A. These results suggest that C, novyi types B and C and C, haemolyticum m ay be one independent species generated from the same phylogenetic origin.