A Gram-stain-negative, aerobic and motile bacterial strain, designated CJ34T, was isolated from Han River water in the Republic of Korea. Strain CJ34T grew optimally on tryptic soy agar at 30 °C and pH 7.0 in the absence of NaCl. Results of phylogenetic analysis based on 16S rRNA gene sequence showed that strain CJ34T belonged to the genus Comamonas within the family Comamonadaceae and was most closely related to Comamonas testosteroni ATCC 11996T and Comamonas thiooxydans DSM 17888T (both 98.63 % similarity). The average nucleotide identity values between strain CJ34T and two closely related type strains C. testosteroni ATCC 11996T and C. thiooxydans DSM 17888T were 82.77 and 82.73 %, respectively. The major isoprenoid quinone of strain CJ34T was ubiquinone Q-8. The major cellular fatty acids of strain CJ34T were C16 : 0, C16 : 1 ω6c and/or C16 : 1 ω7c and C18 : 1 ω6c and/or C18 : 1 ω7c. The predominant polar lipids of strain CJ34T were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and an unidentified aminophospholipid. Whole genome sequencing revealed that strain CJ34T had a genome of 4.9 Mbp and the G+C content of the genomic DNA was 59.73 mol%. On the basis of the results of this polyphasic taxonomy study, strain CJ34T represents a novel species in the genus Comamonas, for which the name Comamonas fluminis sp. nov. is proposed. The type strain is CJ34T (=KACC 22237T=JCM 34454T).
Keywords: 16S rRNA sequences; Comamonas fluminis; Han River; genome; heterogeneity; novel species; phylogenomic tree.