Reclassification of Rhodobium marinum and Rhodobium pfennigii as Afifella marina gen. nov. comb. nov. and Afifella pfennigii comb. nov., a new genus of photoheterotrophic Alphaproteobacteria and emended descriptions of Rhodobium, Rhodobium orientis and Rh

The isolation of photoheterotrophic organism C3 from a saline microbial mat led to its taxonomic characterization. Strain C3 could be identified as a member of the species Rhodobium marinum due to the genetic and phenotypic similarities to the type strain of the species (DSM 2698T). As a result of a taxonomic study, it was observed that the currently classified species of the genus formed two separate clades, each of them deserving genus status. Rhodobium orientis and Rhodobium gokarnense may be considered as true members of the genus Rhodobium, whereas R. marinum and Rhodobium pfennigii should be reclassified into a new genus. In the light of the genetic and phenotypic evidence observed, we propose that both latter species are reclassified within the new genus Afifella gen. nov., as species Afifella marina comb. nov., and Afifella pfennigii comb. nov., with Af. marina the type species of the genus. In addition, the taxonomic study has revealed that strain DSM 11549, identified as the type strain of the species Rhodopseudomonas julia, may represent a genomovar of Af. marina. The fact that the author of the first classification of R. julia indicates that the strains deposited in the German Collection for Microorganisms (DSM 11549) and American Collection of Type Cultures (ATCC 51105) do not correspond to the original description, makes the authenticity of the strains doubtful. Due to this reason, it is not proposed to reclassify the species.