Inference of the phylogenetic position of the phylum Deferribacteres from gene order comparison

The phylogenetic placement of the phylum Deferribacteres was investigated on the basis of gene order comparisons of completely sequenced bacterial genomes. Two completely sequenced Deferribacteres species share five sets of gene arrangements with a group of phyla, Proteobacteria, Aquificae, Planctomycetes, Spirochaetes, Bacteroidetes, Chlorobi, Acidobacteria, Verrucomicrobia, Elusimicrobia and Nitrospirae, while the other group of phyla, Synergistetes, Firmicutes, Actinobacteria, Thermotogae, Chloroflexi and Deinococcus-Thermus, Fusobacteria, shares alternative sets of gene arrangements, suggesting that the Deferribacteres is classified in the former group of phyla. Gene transfers that are thought to have occurred in a common ancestor of the Deferribacteres, Deltaproteobacteria and Nitrospirae exclusive of virtually all other phyla were identified, which suggests that the Deferribacteres is phylogenetically proximal to the Proteobacteria and Nitrospirae.