Abstract

A Gram-reaction-negative, strictly aerobic, non-motile, nonspore-forming, and rod-shaped bacterial strain designated KHI28T was isolated from sediment in Gapcheon (river) and its taxonomic position was investigated using a polyphasic approach. Strain KHI28T grew at 10–42°C and at pH 5.5–8.5 on R2A and nutrient agar without additional NaCl as a supplement. Strain KHI28T possessed β-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb1 and Re (ones of the dominant active components of ginseng) to C-K and Rg2, respectively. On the basis of 16S rRNA gene sequence similarity, strain KHI28T was shown to belong to the family Sphingobacteriaceae and to be related to Mucilaginibacter dorajii DR-f4T (97.9% sequence similarity), M. polysacchareus DRP28T (97.3%), and M. lappiensis ANJLI2 T (97.2%). The G+C content of the genomic DNA was 45.8%. The predominant respiratory quinone was MK-7 and the major fatty acids were summed feature 3 (comprising C16:1 ω6c and/or C16:1 ω7c), iso-C15:0 and C16:0. DNA and chemotaxonomic data supported the affiliation of strain KHI28T to the genus Mucilaginibacter. Strain KHI28T could be differentiated genotypically and phenotypically from the recognized species of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter ginsenosidivorax sp. nov. is proposed, with the type strain KHI28T (=KACC 14955T =LMG 25804T).

• Keywords: 16S rRNA gene; polyphasic taxonomy; Mucilaginibacter ginsenosidivorax; ginsenoside