Sphingobium fluminis sp. nov. and Sphingobium anseongense sp. nov., isolated from riverbank soil

Two novel Gram-stain-negative, aerobic, heterotrophic, motile bacterial strains, designated AN558 T and AN641 T , were isolated from riverbank soil in South Korea. To determine their taxonomic positions, the strains were characterized using a polyphasic taxonomic approach based on 16S rRNA gene phylogeny, phenotypic and chemotaxonomic characteristics and genome-based analyses. Phylogenetic and genome-based analyses revealed that the two novel isolates, AN558 T and AN641 T , belong to the genus Sphingobium . AN558 T showed the highest 16S rRNA gene similarity (97.3%) with Sphingobium yanoikuyae ATCC 51230 T . In addition, AN641 T showed 97.6% 16S rRNA gene similarity with Sphingobium arseniciresistens H39-3-25 T . The genome of strains AN558 T and AN641 T consisted of 3,717,653 and 3,426,895 bp, with DNA G+C content of 62.8 and 63.6 mol%, respectively. The average nucleotide identity between the two strains and other related species was below 79.1%, and the digital DNA–DNA hybridization values with closely related species were below 22.4%, both lower than the species delineation threshold. Strains AN558 T and AN641 T contained ubiquinone Q-10 as the major respiratory quinone and exhibited a polyamine pattern, with spermidine as the predominant polyamine. The major fatty acids were characterized by C 16 : 0 , C 16 : 1 ω7 c / C1 6 : 1 ω6 c (summed feature 3) and C 18 : 1 ω7 c / C1 8 : 1 ω6 c (summed feature 8). The major polar lipids of AN558 T and AN641 T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and phosphatidylcholine. Therefore, AN558 T and AN641 T represent novel species of the genus Sphingobium , for which the names Sphingobium fluminis sp. nov. (type strain AN558 T =KACC 23515 T =LMG 33415 T ) and Sphingobium anseongense sp. nov. (type strain AN641 T =KACC 23516 T =LMG 33416 T ) are proposed.