Sphingopyxis rigui sp. nov. and Sphingopyxis wooponensis sp. nov., isolated from wetland freshwater, and emended description of the genus Sphingopyxis.

Two yellow-pigmented, Gram-reaction-negative strains, designated 01SU5-P(T) and 03SU3-P(T), were isolated from the freshwater of Woopo wetland, Republic of Korea. Both strains were aerobic, non-motile and catalase-negative. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates belong to the genus Sphingopyxis, showing the highest level of sequence similarity with respect to Sphingopyxis witflariensis W-50(T) (95.4-95.7 %). The two novel isolates shared 99.4 % sequence similarity. DNA-DNA hybridization between the isolates and the type strain of S. witflariensis clearly suggested that strains 01SU5-P(T) and 03SU3-P(T) represent two separate novel species in the genus Sphingopyxis. The two strains displayed different fingerprints after PCR analysis using the repetitive primers BOX, ERIC and REP. Several phenotypic characteristics served to differentiate these two isolates from recognized members of the genus Sphingopyxis. The data from the polyphasic study presented here indicated that strains 01SU5-P(T) and 03SU3-P(T) should be classified as representing novel species in the genus Sphingopyxis, for which the names Sphingopyxis rigui sp. nov. and Sphingopyxis wooponensis sp. nov., respectively, are proposed. The type strain of Sphingopyxis rigui sp. nov. is 01SU5-P(T) ( = KCTC 23326(T) = JCM 17509(T)) and the type strain of Sphingopyxis wooponensis sp. nov. is 03SU3-P(T) ( = KCTC 23340(T) = JCM 17547(T)).