Phylogenetic evidence that the gram-negative nonsporulating bacterium Tissierella (Bacteroides) praeacuta is a member of the Clostridium subphylum of the gram-positive bacteria and description of Tissierella creatinini sp. nov.

The 16S rRNA gene sequence of the type strain of Tissierella praeacuta (formerly Bacteroides praeacutus) was determined by PCR direct sequencing. A comparative sequence analysis showed that T. praeacuta is a member of the Clostridium subphylum of the gram-positive bacteria and has a close phylogenetic affinity with the species that form Clostridium cluster XII (M. D. Collins, P. A. Lawson, A. Willems, J. J. Cordoba, J. Fernandez-Garayzabal, P. Garcia, J. Cai, H. Hippe, and J. A. E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994). Although T. praeacuta is gram negative and does not produce endospores, 16S rRNA sequence data showed that it is closely related genealogically (level of sequence similarity, 99.9%) to Clostridium hastiforme. On the basis of our results and the results of previous studies, a second species of Tissierella, Tissierella creatinini sp. nov., is described.