Niastella koreensis gen. nov., sp. nov. and Niastella yeongjuensis sp. nov., novel members of the phylum Bacteroidetes, isolated from soil cultivated with Korean ginseng.

Two novel strains, GR20-10(T) and GR20-13(T), were isolated from soil using R2A medium. The soil sample was collected from a field in the Yeongju region of Korea that was cultivated with Korean ginseng. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains formed a cluster with several uncultured bacterial clones and with Flexibacter filiformis, Flexibacter sancti, Flexibacter japonensis, Cytophaga arvensicola and Flavobacterium ferrugineum (recently reclassified as Terrimonas ferruginea) in the phylum Bacteroidetes. The level of 16S rRNA gene sequence similarity between the two novel strains was 98.9 %. Isolates GR20-10(T) and GR20-13(T) showed the highest sequence similarities to Flexibacter japonensis IFO 16041(T) (91.8 and 91.9 %, respectively) and T. ferruginea ATCC 13524(T) (90.4 and 90.6 %, respectively). The whole-cell fatty acid profiles of the two isolates were similar and their major fatty acids were 15 : 0 iso, 17 : 0 iso 3-OH and 15 : 1 iso G. The major isoprenoid quinone of both strains was MK-7. The G+C contents of GR20-10(T) and GR20-13(T) were 45.8 and 44.3 mol%, respectively. DNA-DNA hybridization (57 % DNA-DNA hybridization value) and phenotypic data indicated that strains GR20-10(T) and GR20-13(T) each belong to a separate species. On the basis of phenotypic and phylogenetic data and genomic distinctiveness, strains GR20-10(T) and GR20-13(T) represent two novel species in a novel genus in the phylum Bacteroidetes; the names Niastella koreensis gen. nov., sp. nov. (the type species; type strain GR20-10(T)=KACC 11465(T)=DSM 17620(T)) and Niastella yeongjuensis sp. nov. (type strain GR20-13(T)=KACC 11466(T)=DSM 17621(T)) are proposed.