Ramlibacter ginsenosidimutans sp. nov., with ginsenoside-converting activity

A novel beta-proteobacterium, designated BXN5-27(T), was isolated from soil of a ginseng field of Baekdu Mountain in China, and was characterized using a polyphasic approach. The strain was Gram-staining-negative, aerobic, motile, non-spore-forming, and rod shaped. Strain BXN5-27(T) exhibited beta-glucosidase activity that was responsible for its ability to transform ginsenoside Rb₁ (one of the dominant active components of ginseng) to compound Rd. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain belonged to the family Comamonadaceae; it was most closely related to Ramlibacter henchirensis TMB834(T) and Ramlibacter tataouinensis TTB310(T) (96.4% and 96.3% similarity, respectively). The G+C content of the genomic DNA was 68.1%. The major menaquinone was Q-8. The major fatty acids were C₁₆:₀, summed feature 4 (comprising C₁₆:₁ omega7c and/or iso-C₁₅:₀ 2OH), and C₁₇:₀ cyclo. Genomic and chemotaxonomic data supported the affiliation of strain BXN5-27(T) to the genus Ramlibacter. However, physiological and biochemical tests differentiated it phenotypically from the other established species of Ramlibacter. Therefore, the isolate represents a novel species, for which the name Ramlibacter ginsenosidimutans sp. nov. is proposed, with the type strain being BXN5-27(T) (= DSM 23480(T) = LMG 24525(T) = KCTC 22276(T)).