<p>Supplemental Material.</p><p>Construction of phylogenetic trees</p><p>All known catalase-peroxidase (KatG) protein sequences were obtained from the PeroxiBase database (http://peroxibase.toulouse.inra.fr/, accessed 7/6/2011) (2) and aligned using MAFFT (1); the sequences for the tree in Figure 1 were extracted from this master alignment. Small subunit rDNA sequences were obtained and aligned via Silva (http://www.arb-silva.de/) (3). The phylogenetic trees were constructed using the neighbor-joining method as implemented in the MEGA5 package (4). Distances for 16S sequences were computed using the Jukes-Cantor model. Distances for KatG amino-acid sequences were computed using a Poisson model of substitution. Both trees were rooted using Escherichia coli strain K12 as an out-group. In both cases, alignment gaps were deleted in a pairwise fashion when computing distance. Bootstrap values were computed from 1000 replicates.</p><p>Alignments, distance matrices, and tree files are available at Dryad (http://dx.doi.org/10.5061/dryad.7j8c5s5j). </p><p>Supplemental references</p><p>1. Katoh, K., K. Misawa, K. Kuma, and T. Miyata. 2002. MAFFT: a novel method for rapid multiple sequence alignment based on fast Fourier transform. Nucleic Acids Res. 30:3059-3066. 2. Koua, D., L. Cerutti, L. Falquet, C. J. A. Sigrist, G. Theiler, N. Hulo, and C. Dunand. 2009. PeroxiBase: a database with new tools for peroxidase family classification. Nucleic Acids Res. 37:D261-D266. 3. Pruesse, E., C. Quast, K. Knittel, B. M. Fuchs, W. G. Ludwig, J. Peplies, and F. O. Glockner. 2007. SILVA: a comprehensive online resource for quality checked and aligned ribosomal RNA sequence data compatible with ARB. Nucleic Acids Res. 35:7188-7196. 4. Tamura, K., D. Peterson, N. Peterson, G. Stecher, M. Nei, and S. Kumar. 2011. MEGA5: Molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol. Biol. Evol. 28:2731- 2739.</p><p>1</p>