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

Abstract

Two novel strains, GR20-10T and GR20-13T, 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 GR20-10T and GR20-13T showed the highest sequence similarities to Flexibacter japonensis IFO 16041T (91.8 and 91.9 %, respectively) and T. ferruginea ATCC 13524T (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 GR20-10T and GR20-13T were 45.8 and 44.3 mol%, respectively. DNA–DNA hybridization (57 % DNA–DNA hybridization value) and phenotypic data indicated that strains GR20-10T and GR20-13T each belong to a separate species. On the basis of phenotypic and phylogenetic data and genomic distinctiveness, strains GR20-10T and GR20-13T 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 GR20-10T=KACC 11465T=DSM 17620T) and Niastella yeongjuensis sp. nov. (type strain GR20-13T=KACC 11466T=DSM 17621T) are proposed.