Phylogenetic basis for a taxonomic dissection of the genus Clostridium

The 16S rDNA-based phylogenetic analysis of the genus Clostridium has been completed by determination of the phylogenetic position of the type strains of 15 species and two non-validated species. These strains are members of phylogenetic clusters I, III, IV, V, IX, XIVa and XVIII as defined previous ly by Collins et al. [Int. J. Syst. Bacteriol. 44 (1994) 812-826]. Members of the genus clostridium span a large evolutionary distance and the genus i s not a phylogenetically coherent taxon but is intermixed with members of d ifferent genera, exhibiting a combination of Clostridium- and non-Clostridi um-type properties. Anaerobacter polyendosporus, Syntrophococcus sucromutan s and Acetivibrio multivorans also cluster within the radiation of Clostrid ium species. Although several taxa have been described for former Clostridi um species with distinct phenotypic properties, the majority of Clostridium species, which are not members of the core cluster I, can at present not b e reclassified as long as taxon-specific, phenotypic properties are not ava ilable. (C) 1999 Federation of European Microbiological Societies. Publishe d by Elsevier Science B.V. All rights reserved.