Sphingomonas aquatica sp nov., isolated from tap water

A Gram-stain-negative, strictly aerobic, rod-shaped bacterium, designated W1-2-1(T), was isolated from tap water in South Korea. The strain was characterized by a polyphasic approach to clarify its taxonomic position. Strain W1-2-1(T) grew at 18-42 degrees C and at pH 6.0-10.0 on R2A medium. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Sphingomonas and is most closely related to the Sphingomonas oligophenolica JCM 12082(T) (97.2% similarity), Sphingomonas asaccharolytica NBRC 15499(T) (96.8 %), Sphingomonas desiccabilis CP1D(T) (96.8 %), Sphingomonas pruni NBRC 15498(T) (96.8 %), Sphingomonas hankookensis ODN7(T) (96.4 %) and Sphingomonas yabuuchiae DSM 14562(T) (95.8 %). Chemotaxonomic data [major ubiquinone - Q10, major polyamine - homospermidine, major fatty acids - summed feature 8 (C-18 (:) (1)omega 7c/omega 6c), C-16 (: 0) and C-14 (: 0) 2-OH and presence of sphingoglycolipid] supported the affiliation of the strain to the genus Sphingomonas. The G+C content of genomic DNA was 67.1 mol%. However, low level of DNA-DNA relatedness value between strain W1-2-1(T) and S. oligophenolica JCM 12082(T) and the results of physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain W1-2-1(T) from other Sphingomonas species with validly published names. Therefore, the isolate represents a novel species, for which the name Sphingomonas aquatica sp. nov. (type strain W1-2-1(T) = KACC 18309(T) = LMG 28596(T)) is proposed.