Figure 1

Phylogenetic tree of pXO1-42 sequences from B. cereus group bacteria (A) and comparison with genetic relationships of the strains (B). Specific groups of strains have been colored to emphasize the incongruence between the two trees. In A), the tree was reconstructed from the nucleotide sequences of pXO1-42 using the Neighbor-Joining method applied to a pairwise distance matrix computed following Tamura's 3-parameter model. For strains with known plasmids, the plasmid name is given in parentheses. Strains whose pXO1-42 sequence contains an intron are shown in bold (intron name given in square brackets and yellow background; due to incomplete sequence data, it could not be confirmed whether strain F65185 carries one or two copies of B.c.I16). Numbered curly brackets indicate four pXO1-42 groups (strains labeled in different colors) sharing identical sequences around the intron's homing site, while remaining strains (in black) have variable sequences not belonging to these groups (sequences shown in Figure 2A). In B), the tree was extracted from a supertree of 1403 isolates based on multiple locus sequence typing (MLST) data of chromosomal housekeeping genes available in the SuperCAT database http://mlstoslo.uio.no/. No MLST data are available for strain BGSC 4I5. Strains whose genome has been completely sequenced are marked with asterisks. In A) and B) numbers next to branch nodes indicate statistical support values when > 50%. Scale bars are in average numbers of nucleotide substitutions per site. Origin and information about the strains can be found at the University of Oslo's typing website, http://mlstoslo.uio.no/. pXO1-42 was identified in four additional strains (AH1271, AH1272, AH1273, and AH717), however they were not included here because their genotyping data are conflicting (see [29])