Chryseobacterium ginsenosidimutans sp. nov., a bacterium with ginsenoside-converting activity isolated from soil of a Rhus vernicifera-cultivated field.

A Gram-reaction-negative, strictly aerobic, non-motile, non-spore-forming, rod-shaped bacterial strain, designated THG 15(T), was isolated from soil of a field cultivated with Rhus vernicifera in Okcheon province, South Korea, and its taxonomic position was investigated by using a polyphasic approach. Strain THG 15(T) grew optimally at 25-30 °C and at pH 7 in the absence of NaCl on nutrient agar. Strain THG 15(T) displayed β-glucosidase (aesculinase) activity that was responsible for its ability to transform ginsenoside Rb(1) (one of the dominant active components of ginseng) into compound K via Rd and F(2). On the basis of 16S rRNA gene sequence similarities, strain THG 15(T) was shown to belong to the family Flavobacteriaceae and was most closely related to Chryseobacterium soldanellicola PSD1-4(T) (97.7 % sequence similarity), Chryseobacterium soli JS6-6(T) (97.5 %) and Chryseobacterium indoltheticum LMG 4025(T) (97.3 %). The G+C content of the genomic DNA was 35.7 mol%. The major menaquinone was MK-6 and the major fatty acids were iso-C(15 : 0) (50.3 %), iso-C(17 : 0) 3-OH (21.9 %), summed feature 4 (comprising C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH; 9.5 %) and iso-C(17 : 1)ω9c (9.3 %). DNA sequence analysis and chemotaxonomic data supported the affiliation of strain THG 15(T) to the genus Chryseobacterium. DNA-DNA relatedness values between strain THG 15(T) and its closest phylogenetic neighbours were <15 %. Strain THG 15(T) could be differentiated genotypically and phenotypically from recognized species of the genus Chryseobacterium. The isolate therefore represents a novel species, for which the name Chryseobacterium ginsenosidimutans sp. nov. is proposed. The type strain is THG 15(T) ( = KACC 14527(T)  = JCM 16719(T)).