Proposal of Sphingomonas wittichii sp nov for strain RW1T, known as a dibenzo-p-dioxin metabolizer

A polyphasic taxonomic study was performed on Sphingomonas sp, strain RW1(T). The organism was isolated from water of the River Elbe and has been known as a potent metabolizer of dibenzo-p-dioxin and its relatives. TLC of a mild alkaline hydrolysate of extractable cellular lipids of strain RW1(T) and type strains of 21 Sphingomonas species gave a spot of sphingoglycolipid (SGL)-1 (glucuronosyl ceramide), which is characteristic of sphingomonads. In addition, strain RW1(T) and type strains of three Sphingomonas species (Sphingomonas yanoikuyae, Sphingomonas terrae and Sphingomonas macrogoltabidus) showed a second spot of SGL (SGL-1) identified as galacturonosyl ceramide. The presence of SGL-1 in cellular lipids suggested that strain RW1(T) is a member of the genus Sphingomonas. DNA-DNA reassociation rates between strain RW1(T) and each type strain of 14 Sphingomonas species including Sphingomonas paucimobilis, type species for the genus, revealed that strain RW1(T) is independent from these species. Results of phylogenetic analysis of 16S rDNA sequences of strain RW1(T) and type strains of 21 named Sphingomonas species verified that strain RW1(T) belongs to the genus Sphingomonas. Strain RW1(T) could be differentiated from named species of the genus by phenotypic characteristics and has been assigned to a new species, Sphingomonas wittichii sp. nov. The type strain is DSM 6014(T) (= JCM 10273(T) = EY 4224(T)). DNA G+C content is 67 mol%.