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

Abstract

Two aerobic, Gram-stain-negative, gliding and yellow-pigmented bacteria, designated strains 03SUJ6T and WM95T 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 WM95T was 97.7 %, but their DNA-DNA relatedness was 55.1 %. A maximum-likelihood phylogenetic tree based on 16S rRNA gene sequences showed that 03SUJ6T and WM95T each form independent lineages within the genus Sphingomonas. 03SUJ6T was related distantly to Sphingomonas daechungensis CH15-11T (97.4 % 16S rRNA gene sequence similarity), Sphingomonas ginsengisoliGsoil 634T (97.3 %) and Sphingomonas astaxanthinifaciens DMS 22298T (97.1 %). Closest relatives of strain WM95T were S. daechungensis CH15-11T (98.2 %), Sphingomonasjaspsi DSM 18422T (97.6 %), Sphingomonas sediminicolaDae 20T (97.5 %), Sphingomonaslutea JS5T (97.4 %) and S. ginsengisoliGsoil 634T (97.2 %). The major fatty acids of the two isolates were summed feature 8 and C16 : 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 03SUJ6T and WM95T 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 03SUJ6T (=KCTC 23331T=JCM 17543T) and strain WM95T (=KACC 18738T=JCM 31399T), respectively.