*Gemmatimonas (Gemmatimonadales)*

Most significantly, *Gemmatimonas phototrophica* was found at the deepest branching point in the RNA tree, which placed this bacterium apart from all other phototrophic purple bacteria and also the phototrophic green bacteria. However, with the *Proteobacteria,* it shared the type-2 photosystem. In the PS tree, it formed a distinct line that split off at the deepest branching point from the *Burkholderiales* and was distantly linked to *Rubrivivax* (*Betaproteobacteria*). This was an indication that the photosynthetic roots of *Gemmatimonas* were associated with the ancient roots of the phototrophic *Burkholderiales*. If we exclude the acquisition of a foreign 16S rRNA, the most likely explanation for this discrepancy would be the acquirement of the photosynthesis genes by an early ancestor of *Gemmatimonas*, as suggested by Zeng et al. [26]. This event should have preceded the branching divergence of the *Burkholderiales.*
