Abstract

A Gram-reaction negative, strictly aerobic, non-motile, orange colored, and rod-shaped bacterium (designated BS26T) isolated from compost, was characterized by a polyphasic approach to clarify its taxonomic position. Strain BS26T was observed to grow optimally at 25–30°C and at pH 7.0 on R2A and nutrient media. Strain BS26T showed β-glucosidase activity that was responsible for its ability to transform ginsenoside Rb1 (one of the active components of ginseng) to ginsenoside compound-K (C-K). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BS26T belongs to the genus Niabella of family Chitinophagaceae and was most closely related to Niabella soli DSM 19437T (94.5% similarity), N. yanshanensis CCBAU 05354T (94.3%), and N. aurantiaca DSM 17617T (93.8%). The G+C content of genomic DNA was 47.3 mol%. Chemotaxonomic data [predominant isoprenoid quinone-MK-7, major fatty acids–iso-C15:0, iso-C15:1 G, iso-C17:0 3-OH, and summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c)] supported the affiliation of strain BS26T to the genus Niabella. However, strain BS26T could be differentiated genotypically and phenotypically from the recognized species of the genus Niabella. The novel isolate therefore represents a novel species, for which the name Niabella ginsenosidivorans sp. nov. is proposed, with the type strain BS26T (=KACC 16620T =JCM 18199T).

• Keywords: Niabella ginsenosidivorans; 16S rRNA gene sequence; polyphasic taxonomy; ginsenoside; decayed feedstuff; compost