Figure 1.

Phylogenetic tree highlighting the position of B. helcogenes relative to those type strains within the genus that appeared within a monophyletic Bacteroides main clade in preliminary analyses. Note that several of the Bacteroides type strain 16S rRNA sequences (from B. cellulosolvens, B. galacturonicus, B. pectinophilus, B. vulgatus) did not cluster together with this clade (data not shown, but see [5]) and were omitted from the main phylogenetic inference analysis. The same holds for the sequence from Anaerorhabdus furcosa (GU585668; also Bacteroidaceae). Other Bacteroides species lacked a sufficiently long 16S rRNA sequence and also had to be omitted (B. coagulans, B. xylanolyticus). The tree was inferred from 1,414 aligned characters [6–7] of the 16S rRNA gene sequence under the maximum likelihood criterion [8] and rooted with the type strain of the family ‘Prevotellaceae’. The branches are scaled in terms of the expected number of substitutions per site. Numbers above branches are support values from 1,000 bootstrap replicates [9] if larger than 60%. Lineages with type strain genome sequencing projects registered in GOLD [10] are shown in blue, published genomes [11] and Prevotella melaninogenica released Genbank accession CP002122 in bold.