Figure 9.

Proteomic tree of 33 bacteria with nitrogen fixation capabilities. The probe-set classification tree of the 33 nitrogen-fixing microorganisms recorded in the GOLD database [27]. Each leaf is labelled with the taxonomic ID of the organism, and the labels on the outer tracks indicate the phyla of the species. Similar to the result shown in Figure 6 for the photosynthesis microbes, the clustering of these nitrogen-fixing microorganisms is consistent with the taxonomic classification of these species. Notably, L. ferrodiazotrophum, the genome of which is only partially sequenced, is correctly clustered with T. yellowstonii (taxonomic ID: 289376), a species that belongs to the same phylum with L. ferrodiazotrophum, i.e., Nirtospirae.