Abstract

The Gram-reaction-negative, strictly aerobic, non-motile, non-spore-forming, and rod-shaped bacterial strain designated Gsoil 1429T was isolated from the soil of ginseng cultivating field of Pocheon province in South Korea. This bacterium was characterized in order to determine its taxonomic position by using the polyphasic approach. Strain Gsoil 1429T grew well at 25-37°C and at pH 7.0 on R2A and nutrient agar without NaCl supplement. Strain Gsoil 1429T had beta-glucosidase activity, which was responsible for its ability to transform ginsenoside Rb1 (one of the dominant active components of ginseng) to F2 via gypenoside XVII. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 1429T was shown to belong to the family Sphingomonadaceae and to be related to Sphingomonas yunnanensis YIM 003T (98.2% sequence similarity), S. phyllosphaerae FA2T (97.5%), S. koreensis JSS26T (97.3%), and S. asaccharolytica IFO 15499T (97.1%). The G+C content of the genomic DNA was 65.6%. The major respiratory quinone was Q-10 and the major fatty acids were summed feature 8 (comprising C18:1 w7c/w9t/w12t), C16:0 and C14:0 2OH. DNA and chemotaxonomic data supported the affiliation of strain Gsoil 1429T to the genus Sphingomonas. The DNA-DNA relatedness values between strain Gsoil 1429T and its closest phylogenetically neighbours were below 28%. Strain Gsoil 1429T could be differentiated genotypically and phenotypically from the recognized species of the genus Sphingomonas. The isolate therefore represents a novel species, for which the name Sphingomonas ginsenosidimutans sp. nov. is proposed, with the type strain Gsoil 1429T (=KACC 14949T =JCM 17074T =LMG 25799T).

• Keywords: 16S rRNA gene; polyphasic taxonomy; S. ginsenosidimutans; ginsenoside