Fig. 1

Heat map showing the distribution of α-subunit homologs of thermophilic RO terminal oxygenases among other thermophilic and mesophilic bacteria. Each thermophilic homolog (represented by the corresponding protein name or locus tag followed by the accession number and strain name) was used as a blastp query, and only entries equal to or exceeding the threshold identity of 40% and query coverage of 80% were considered to be positive hits. The distribution is categorized into different taxa (or taxonomic hierarchies), shown on the top, with bacteria belonging to each phylum grouped separately as thermophiles and mesophiles (highlighted with yellow and green backgrounds, respectively). In the heat map, each cell is divided into two blocks; the upper (wider) block shows the percentage identity obtained from blastp, while the lower (narrower) block indicates the number of distinct species obtained from the blast search. Color codes used for each identity range are shown as an inset. Values corresponding to each cell can be obtained from Additional file 1: Table S1