Figure 1.
The natural distribution of spf. spf is restricted to 5 orders of gamma-proteobacteria (shown in bold letters), 4 of which share the same closest common ancestor (indicated by an arrow). The circular phylogenetic tree (made using the iTol web tool) shows all major branches of Bacteria. The gamma-proteobacteria phylogeny in the right panel is based on Gao et al.25 Here, numbers in parentheses indicate the number of complete genomes that contain spf (first number) and the total number of available complete genomes (second number) in each order. In addition, spf is found in 8 Chromatiales draft genomes (asterisk).