Analysis of marine cyanobacteria and proteobacteria genomes has provided a profound understanding of the life strategies of these organisms and their ecotype differentiation and metabolisms. However, a comparable analysis of the Bacteroidetes, the third major bacterioplankton group, is still lacking. In the present paper, we report on the genome of Polaribacter sp. strain MED152. On the one hand, MED152 contains a substantial number of genes for attachment to surfaces or particles, gliding motility, and polymer degradation. This agrees with the currently assumed life strategy of marine Bacteroidetes. On the other hand, it contains the proteorhodopsin gene, together with a remarkable suite of genes to sense and respond to light, which may provide a survival advantage in the nutrient-poor sun-lit ocean surface when in search of fresh particles to colonize. Furthermore, an increase in CO2 fixation in the light suggests that the limited central metabolism is complemented by anaplerotic inorganic carbon fixation. This is mediated by a unique combination of membrane transporters and carboxylases. This suggests a dual life strategy that, if confirmed experimentally, would be notably different from what is known of the two other main bacterial groups (the autotrophic cyanobacteria and the heterotrophic proteobacteria) in the surface oceans. The Polaribacter genome provides insights into the physiological capabilities of proteorhodopsin-containing bacteria. The genome will serve as a model to study the cellular and molecular processes in bacteria that express proteorhodopsin, their adaptation to the oceanic environment, and their role in carbon-cycling.Bacteroidetes ͉ marine bacteria ͉ whole-genome analysis ͉ heterotrophic CO2 fixation

The taxonomic position of a marine, gliding, pink-pigmented, aerobic, heterotrophic and Gram-negative bacterium was established using a polyphasic approach. 16S rRNA gene sequence analysis indicated that the strain was a member of the phylum ‘Bacteroidetes’ in which it occupied a separate lineage. The predominant cellular fatty acids were C15 : 0 iso, C17 : 0 iso 3-OH, summed feature 3 and summed feature 4. The DNA G+C content was 48·7 mol%. Phylogenetic evidence and the results of phenotypic, genotypic and chemotaxonomic analyses strongly support the assignment of the newly isolated bacterium as a member of a novel genus and species, for which the name Pontibacter actiniarum gen. nov., sp. nov. is proposed. The type strain is KMM 6156T (=KCTC 12367T=LMG 23027T). It is also proposed that the illegitimate names Reichenbachia and Reichenbachia agariperforans are replaced with Reichenbachiella and Reichenbachiella agariperforans, respectively.

Three novel heterotrophic, Gram-negative, yellow-pigmented, aerobic, gliding, oxidase- and catalase-positive bacteria were isolated from algae collected in the Gulf of Peter the Great, Sea of Japan. 16S rRNA gene sequence analysis revealed that the strains studied represented members of the family Flavobacteriaceae and showed 93·5–93·8 % similarity with their closest relative, Psychroserpens burtonensis. The DNA G+C content of the strains was 34–37 mol%. The major respiratory quinone was MK-6. The predominant fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C15 : 1, iso-C16 : 0-3OH and iso-C17 : 0-3OH. On the basis of their phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, the newly described bacteria have been assigned to the new genus Winogradskyella gen. nov., as Winogradskyella thalassocola sp. nov. (type strain, KMM 3907T=KCTC 12221T=LMG 22492T=DSM 15363T), Winogradskyella epiphytica sp. nov. (type strain, KMM 3906T=KCTC 12220T=LMG 22491T=CCUG 47091T) and Winogradskyella eximia sp. nov. (type strain, KMM 3944T (=KCTC 12219T=LMG 22474T).

Six novel gliding, heterotrophic, Gram-negative, yellow-pigmented, aerobic, oxidase- and catalase-positive bacteria were isolated from the green alga Ulva fenestrata, sea water and a bottom sediment sample collected in the Gulf of Peter the Great, Sea of Japan. 16S rRNA gene sequence analysis revealed that the strains studied were members of the family Flavobacteriaceae. On the basis of their phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, the novel bacteria have been assigned to the new genus Maribacter gen. nov., as Maribacter sedimenticola sp. nov., Maribacter orientalis sp. nov., Maribacter aquivivus sp. nov. and Maribacter ulvicola sp. nov., with the type strains KMM 3903T (=KCTC 12966T=CCUG 47098T), KMM 3947T (=KCTC 12967T=CCUG 48008T), KMM 3949T (=KCTC 12968T=CCUG 48009T) and KMM 3951T (=KCTC 12969T=DSM 15366T), respectively.

Mesonia algae gen. nov., sp. nov., a novel marine bacterium of the family Flavobacteriaceae isolated from the green alga Acrosiphonia sonderi (Kü tz) Kornm The taxonomic position of four heterotrophic, aerobic, Gram-negative, non-motile and moderately halophilic marine bacteria, isolated from the green alga Acrosiphonia sonderi (Kü tz) Kornm, was established. 16S rDNA sequence analysis indicated that the strains studied are members of the family Flavobacteriaceae, in which they form a distinct lineage. On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic data, the novel bacteria were classified as Mesonia algae gen. nov., sp. nov. The type strain is KMM 3909 T (=KCTC 12089 T =CCUG 47092 T ).