Ohtaekwangia koreensis gen. nov., sp. nov. and Ohtaekwangia kribbensis sp. nov., isolated from marine sand, deep-branching members of the phylum Bacteroidetes

Abstract

Two Gram-stain-negative, non-motile, non-spore-forming, rod-shaped bacterial strains, designated 3B-2(T) and 10AO(T), were isolated from a sand sample collected from the west coast of the Korean peninsula by using low-nutrient media, and their taxonomic positions were investigated in a polyphasic study. The strains did not grow on marine agar. They grew optimally at 30 °C and pH 6.5-7.5. Strains 3B-2(T) and 10AO(T) shared 97.5 % 16S rRNA gene sequence similarity and mean level of DNA-DNA relatedness of 12 %. In phylogenetic trees based on 16S rRNA gene sequences, strains 3B-2(T) and 10AO(T), together with several uncultured bacterial clones, formed independent lineages within the evolutionary radiation encompassed by the phylum Bacteroidetes. Strains 3B-2(T) and 10AO(T) contained MK-7 as the predominant menaquinone and iso-C(15 : 0) and C(16 : 1)ω5c as the major fatty acids. The DNA G+C contents of strains 3B-2(T) and 10AO(T) were 42.8 and 44.6 mol%, respectively. Strains 3B-2(T) and 10AO(T) exhibited very low levels of 16S rRNA gene sequence similarity (<85.0 %) to the type strains of recognized bacterial species. These data were sufficient to support the proposal that the novel strains should be differentiated from previously known genera of the phylum Bacteroidetes. On the basis of the data presented, we suggest that strains 3B-2(T) and 10AO(T) represent two distinct novel species of a new genus, for which the names Ohtaekwangia koreensis gen. nov., sp. nov. (the type species; type strain 3B-2(T) = KCTC 23018(T) = CCUG 58939(T)) and Ohtaekwangia kribbensis sp. nov. (type strain 10AO(T) = KCTC 23019(T) = CCUG 58938(T)) are proposed.