Sphingobacterium ginsenosidimutans sp. nov., a bacterium with ginsenoside-converting activity isolated from the soil of a ginseng field

Abstract

A Gram-staining-negative, aerobic, non-motile, non-spore-forming, and rod-shaped bacterium designated THG 07(T) was isolated from the soil of a ginseng field of Pocheon in South Korea, and its taxonomic position was investigated by using a polyphasic study. Strain THG 07(T) grew optimally at 25-30°C and at pH 6.5-7.0 and in the absence of NaCl on nutrient agar. Strain THG-T17(T) displayed β-glucosidase activity that was responsible for its ability to transform ginsenoside Rb1 (one of the dominant ginsenosides of ginseng) to compound C-K. On the basis of 16S rRNA gene sequence similarity, strain THG 07(T) was shown to belong to the family Sphingobacteriaceae and was related to Sphingobacterium canadense CR11(T) (98.7%), S. cladoniae No.6(T) (98.1%), S. detergens 6.2S(T) (98.0%), S. multivorum IAM14316(T) (97.9%), S. siyangense SY1(T) (97.8%) and S. thalpophilum DSM11723(T) (96.9%). The G+C content of the genomic DNA was 40.6 mol%. The major menaquinone, MK-7, and major fatty acids, iso-C₁₅:₀ and C₁₆:₁ ω7c and/or ω6c, supported the affiliation of strain THG 07(T) to the genus Sphingobacterium. The DNA-DNA relatedness values between strain THG 07(T) and its closest phylogenetic neighbors were below 26.9%. The results of physiological and biochemical tests enabled strain THG 07(T) to be differentiated phenotypically from the recognized species of the genus Sphingobacterium. Therefore the isolate represents a novel species, for which the name Sphingobacterium ginsenosidimutans sp. nov. is proposed, with the type strain THG 07(T) (=KACC 14526(T)=JCM 16722(T)).