The novel bacterial strain C33T was isolated from a freshwater sample collected from the Hapcheon-Changnyeong barrage. The Gram-negative, motile, yellow-pigmented strain C33T was characterized as a rod-shaped and strictly aerobic bacterium. A 16S-rRNA phylogenetic analysis revealed that this strain was most closely related to Sphingomonas changbaiensis V2M44T, Sphingomonas tabacisoli X1-8T, and Sphingomonas flavalba ZLT-5T with 97.1, 97.0, and 95.0 % 16S-rRNA sequence similarities, respectively. The genomic DNA GC content of strain C33T was estimated at 65.0 mol%. The average nucleotide identity of strain C33T relative to S. changbaiensis V2M44T and S. flavalba ZLT-5T was found to be 77.0 and 75.6%, with average amino-acid identities of 69.9, and 66.7%, and the digital DNA-DNA hybridization values of 21.3 and 17.7 %, respectively. The cells grew at 19-37 °C and pH 6-9 with 0-0.5 % (w/v) NaCl (optimum: 28 °C, pH 6.5, and 0 % NaCl). The major component identified in the polyamine pattern was sym-homospermidine, and the main ubiquinone was Q-10. The predominant polar lipids characterized were diphophatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, and sphingoglycolipid. Iso-C15 : 0, C15 : 0 anteiso, and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) were found to be the primary cellular fatty acids in strain C33T. Based on these genotypic and phenotypic characteristics, strain C33T was classified as a novel species of the genus Sphingomonas; and the name Sphingomonas changnyeongensis sp. nov. is proposed (=KACC 21511T=JCM 33880T).
Keywords: Alphaproteobacteria; Sphingomonas; freshwater; sphingoglycolipid; taxonomy; ubiquinone Q10.