Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Research article

Taxonomy and evolution of bacteriochlorophyll a-containing members of the OM60/NOR5 clade of marine gammaproteobacteria: description of Luminiphilus syltensis gen. nov., sp. nov., reclassification of Haliea rubra as Pseudohaliea rubra gen. nov., comb. nov., and emendation of Chromatocurvus halotolerans

Stefan Spring1*, Thomas Riedel25, Cathrin Spröer1, Shi Yan36, Jens Harder4 and Bernhard M Fuchs3

Author Affiliations

1 Leibniz Institute DSMZ, German Collection of Microorganisms and Cell Cultures, Inhoffenstr. 7B, Braunschweig 38124, Germany

2 Helmholtz-Centre for Infection Research (HZI), Research Group Microbial Communication, Inhoffenstr. 7, Braunschweig 38124, Germany

3 Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Celsiusstr. 1, Bremen 28359, Germany

4 Department of Microbiology, Max Planck Institute for Marine Microbiology, Celsiusstr. 1, Bremen 28359, Germany

5 Present address: Observatoire Océanologique de Banyuls, Université P. et M. Curie, UMR-CNRS 7621, Laboratoire Arago, Banyuls-sur-Mer 66650, France

6 Present address: Group of Computational Genetics, CAS-MPG Partner Institute for Computational Biology, SIBS, CAS, Shanghai 200433, China

For all author emails, please log on.

BMC Microbiology 2013, 13:118  doi:10.1186/1471-2180-13-118

Published: 24 May 2013

Abstract

Background

Aerobic gammaproteobacteria affiliated to the OM60/NOR5 clade are widespread in saline environments and of ecological importance in several marine ecosystems, especially the euphotic zone of coastal areas. Within this group a close relationship between aerobic anoxygenic photoheterotrophs and non-phototrophic members has been found.

Results

Several strains of aerobic red-pigmented bacteria affiliated to the OM60/NOR5 clade were obtained from tidal flat sediment samples at the island of Sylt (North Sea, Germany). Two of the novel isolates, Rap1red and Ivo14T, were chosen for an analysis in detail. Strain Rap1red shared a 16S rRNA sequence identity of 99% with the type strain of Congregibacter litoralis and was genome-sequenced to reveal the extent of genetic microheterogeneity among closely related strains within this clade. In addition, a draft genome sequence was obtained from the isolate Ivo14T, which belongs to the environmental important NOR5-1 lineage that contains so far no cultured representative with a comprehensive description. Strain Ivo14T was characterized using a polyphasic approach and compared with other red-pigmented members of the OM60/NOR5 clade, including Congregibacter litoralis DSM 17192T, Haliea rubra DSM 19751T and Chromatocurvus halotolerans DSM 23344T. All analyzed strains contained bacteriochlorophyll a and spirilloxanthin as photosynthetic pigments. Besides a detailed phenotypic characterization including physiological and chemotaxonomic traits, sequence information based on protein-coding genes and a comparison of draft genome data sets were used to identify possible features characteristic for distinct taxa within this clade.

Conclusions

Comparative sequence analyses of the pufLM genes of genome-sequenced representatives of the OM60/NOR5 clade indicated that the photosynthetic apparatus of these species was derived from a common ancestor and not acquired by multiple horizontal gene transfer from phylogenetically distant species. An affiliation of the characterized bacteriochlorophyll a-containing strains to different genera was indicated by significant phenotypic differences and pufLM nucleotide sequence identity values below 82%. The revealed high genotypic and phenotypic diversity of closely related strains within this phylogenetic group reflects a rapid evolution and frequent niche separation in the OM60/NOR5 clade, which is possibly driven by the necessities of an adaptation to oligotrophic marine habitats.

Keywords:
Phylogeny; Aerobic anoxygenic photoheterotroph; Proteorhodopsin; Mixotroph; Picoplankton; Coastal marine environment