Fulvimarina pelagi gen. nov., sp. nov., a marine bacterium that forms a deep evolutionary lineage of descent in the order "Rhizobiales".

Abstract

Three brownish-yellow bacterial strains were isolated from the western Sargasso Sea by high-throughput culturing methods and characterized by polyphasic approaches. All isolates were Gram-negative, strictly aerobic, chemoheterotrophic, non-motile short rods that contained carotenoid pigments. Phylogenetic analyses based on 16S rRNA gene sequences, DNA-DNA hybridization and DNA G+C content, along with phenotypic characteristics, revealed that they belonged to the same species. The strains utilized a wide range of substrates, including pentoses, hexoses, oligosaccharides, sugar alcohols, organic acids and amino acids, as sole carbon sources. The DNA G+C content of the isolates ranged from 57.6 to 59.9 mol%. The predominant cellular fatty acid constituent was C(18 : 1)omega7c, whilst C(16 : 0), C(18 : 0) and C(19 : 0)omega8c cyclo were also abundant. The organism related most closely to these strains, as determined by 16S rDNA sequence comparison, was the recently described species Aurantimonas coralicida (93.3-93.8 % similarity). Phylogenetic analyses indicated that the strains formed a distinct and deep evolutionary lineage of descent, together with A. coralicida, within the order "Rhizobiales" of the alpha-Proteobacteria. This lineage could not be associated with any of the ten known families in the order "Rhizobiales". From polyphasic evidence, it is proposed that the strains be placed into a novel genus and species, Fulvimarina pelagi gen. nov., sp. nov. (type strain, HTCC2506(T)=ATCC BAA-666(T)=KCTC 12091(T)=DSM 15513(T)).