ASSIGNMENT OF THE AGENT OF TYZZERS DISEASE TO CLOSTRIDIUM-PILIFORME COMB-NOV ON THE BASIS OF 16S RIBOSOMAL-RNA SEQUENCE-ANALYSIS

The small-subunit rRNA (16S rRNA) sequence of Tyzzer's bacillus (also known as ''Bacillus piliformis'') was elucidated by using the polymera se chain reaction followed by reverse transcriptase sequencing. By usi ng maximum-likelihood analysis, a phylogenetic tree was constructed fr om this and other 16S rRNA sequences available from the first release of the Ribosomal Database Project (G. J. Olsen, R. Overbeek, N. Larsen , T. L. Marsh, M. J. McCaughey, M. A. Maciukenas, W.-M. Kuan, T. J. Ma cke, Y. Xing, and C. R. Woese, Nucleic Acids Res. 20:2199-2200, 1992). Tyzzer's bacillus grouped with a specific set of anaerobic bacteria, most of which are Clostridium spp. The closest identified relatives ar e Clostridium coccoides, Clostridium oroticum, Clostridium clostridiif orme, Clostridium symbiosum, and Streptococcus hansenii. Clostridium a minovalericum and ''Acetitomaculum ruminis'' are also solidly allied w ith this ensemble. We propose that Tyzzer's bacillus be reclassified a s Clostridium piliforme on the basis of its 16S rRNA sequence.