Fig. 1.

—Phylogenetic reconstruction of Clostridium species. Left corner: core protein families identified at different sequence identity cut-offs in all genomes and in genomes located in cluster I. The phylogeny was constructed using 27 markers conserved across 779 genomes (supplementary table S1, Supplementary Material online) deposited in the GenBank database and taxonomically defined as Clostridium. The main clades outside (blue lines) and within (369 taxa, red lines) the cluster I sensu stricto group (real clostridia) have been collapsed and defined as 17 taxonomic subgroups (table 1). Branch support is shown at each node. Uncollapsed clades for subgroups 1–17 are shown in supplementary figures S1–S14, Supplementary Material online.