In this study, a comprehensive phenotypic and genotypic characterization of the novel isolate Ivo14T was performed that DAPT allowed a detailed comparison to other bacteriochlorophyll (BChl) a-containing members of the OM60/NOR5 clade, so that a profound knowledge of the metabolic plasticity and taxonomic relationships encountered in this ecologically important group of marine gammaproteobacteria could be obtained. Results and discussion Isolation and identification of mixotrophic representatives of the OM60/NOR5 clade An isolation strategy originally designed for the retrieval of strains belonging to the genus Rhodopirellula within the Planctomycetales

resulted in the isolation of numerous representatives of the OM60/NOR5 clade of marine gammaproteobacteria [13, 25]. The isolation strategy included the use of antibiotics and a screening of red-pigmented strains,

so that all retrieved OM60/NOR5 isolates were pigmented. Strains belonging to this phylogenetic group represented about 10% of all red-pigmented colonies and could be affiliated either to the NOR5-3 or NOR5-1 lineage within this clade based on analyses of their 16S rRNA gene sequences [13]. Strains belonging to the OM60/NOR5 clade were further examined for the presence of pufL and pufM genes encoding proteins Inhibitor Library of the photosynthetic reaction center. From 18 out of 22 isolated strains fragments of pufLM genes could be amplified by PCR using specific primers. Probably, the strategy of Winkelmann and Harder [25] was such an effective method for the isolation of mixotrophic members Mannose-binding protein-associated serine protease of the OM60/NOR5 clade, because it selected for pigmented and slowly growing

bacteria adapted to oligotrophic habitats. Two of the isolated strains, Rap1red (= NOR5-3) and Ivo14T (= NOR5-1BT), representing two different lineages of the OM60/NOR5 clade were selected for a further analysis using genome sequencing. Strain Ivo14T representing the highly diverse and environmentally important NOR5-1 lineage was chosen for an additional detailed phenotypic characterization. Noteworthy, Haliea rubra (H. rubra), which is closely related to C. litoralis was also reported to form red-pigmented colonies on Marine Agar 2216 [18], but in the original species description the formation of photosynthetic pigments was not reported. To exclude the possibility that a phototrophic phenotype has escaped attention in described strains of the genus Haliea, type strains belonging to this genus were cultured in SYPHC medium, which allowed expression of pigments in all photoheterotrophic strains belonging to the OM60/NOR5 clade tested so far. In fact, photosynthetic pigments could be extracted from cells of H.