Rhodoferax

Rhodoferax is a genus of Betaproteobacteria belonging to the purple nonsulfur bacteria. Originally, Rhodoferax species were included in the genus Rhodocyclus as the Rhodocyclus gelatinous-like group. The genus Rhodoferax was first proposed in 1991 to accommodate the taxonomic and phylogenetic discrepancies arising from its inclusion in the genus Rhodocyclus. Rhodoferax currently comprises four described species: R. fermentans, R. antarcticus, R. ferrireducens, and R. saidenbachensis. R. ferrireducens, lacks the typical phototrophic character common to two other Rhodoferax species. This difference has led researchers to propose the creation of a new genus, Albidoferax, to accommodate this divergent species. The genus name was later corrected to Albidiferax. Based on geno- and phenotypical characteristics, A. ferrireducens was reclassified in the genus Rhodoferax in 2014. R. saidenbachensis, a second non-phototrophic species of the genus Rhodoferax was described by Kaden et al. in 2014.''

== Taxonomy == Rhodoferax species are Gram-negative rods, ranging in diameter from 0.5 to 0.9 μm with a single polar flagellum. The first two species described for the genus, R. fermentans and R. antarcticus, are facultative photoheterotrophs that can grow anaerobically when exposed to light and aerobically under dark conditions at atmospheric levels of oxygen. R. ferrireducens is a nonphototrophic facultative anaerobe capable of reducing Fe(III) at temperatures as low as 4 °C. R. saidenbachensis grows strictly aerobic and has a very low rate of cell division. All Rhodoferax species possess ubiquinone and rhodoquinone derivatives with eight unit isoprenoid side chains. Dominant fatty acids in Rhodoferax cells are palmitoleic acid (16:1) and palmitic acid (16:0), as well as 3-OH octanoic acid (8:0). Major carotenoids found in the phototrophic species are spheroidene, OH-spheroidene, and spirilloxanthin.