Sphingomonas limnosediminicola sp nov and Sphingomonas palustris sp nov., isolated from freshwater environments

Two aerobic, Gram-stain-negative, gliding and yellow-pigmented bacteria, designated strains 03SUJ6(T) and WM95(T) were isolated from freshwater sediment of Juam reservoir and freshwater of Woopo wetland, Republic of Korea, respectively. Cells of the two strains are motile by gliding and catalase-and oxidase-positive. The 16S rRNA gene sequence similarity between 03SUJ6T and WM95(T) was 97.7 %, but their DNA-DNA relatedness was 55.1 %. A maximum-likelihood phylogenetic tree based on 16S rRNA gene sequences showed that 03SUJ6(T) and WM95(T) each form independent lineages within the genus Sphingomonas. 03SUJ6T was related distantly to Sphingomonas daechungensis CH15-11(T) (97.4% 16S rRNA gene sequence similarity), Sphingomonas ginsengisoli Gsoil 634(T) (97.3 %) and Sphingomonas astaxanthinifaciens DMS 22298(T) (97.1 %). Closest relatives of strain WM95(T) were S. daechungensis CH15-11(T) (98.2 %), Sphingomonas jaspsi DSM 18422(T) (97.6 %), Sphingomonas sediminicola Dae 20(T) (97.5 %), Sphingomonas lutea JS5(T) (97.4 %) and S. ginsengisoli Gsoil 634(T) (97.2 %). The major fatty acids of the two isolates were summed feature 8 and C-16 : 0. The predominant isoprenoid quinone was ubiquinone-10. The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. sym-Homospermidine was the major polyamine of the isolates. Phenotypic characteristics distinguished 03SUJ6(T) and WM99(T) from the related species of the genus Sphingomonas. On the basis of the evidence presented in this study, the novel species, Sphingomonas limnosediminicola sp. nov. and Sphingomonas palustris sp. nov. are proposed for strain 03SUJ6(T) (= KCTC 23331(T) = JCM 17543(T)) and strain WM95(T) (= KACC 18738(T) = JCM 31399(T)), respectively.