Mucilaginibacter pocheonensis sp. nov., with ginsenoside-converting activity, isolated from soil of a ginseng-cultivating field.

Abstract

A Gram-reaction-negative, aerobic, heterotrophic, non-motile, non-spore-forming, rod-shaped bacterial strain, designated Gsoil 032T, was isolated from soil of a ginseng field in Pocheon Province, South Korea, and its taxonomic position was investigated by using a polyphasic approach. Strain Gsoil 032T grew at 10-42 °C and at pH 5.0-10.0 on R2A agar medium. Strain Gsoil 032T possessed β-glucosidase activity, which was responsible for its ability to transform ginsenoside Rb1 (one of the dominant active components of ginseng) to compound K. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 032T was shown to belong to the family Sphingobacteriaceae and to be related to Mucilaginibacter sabulilitoris SMS-12T (97.6 % sequence similarity) and Mucilaginibacter lappiensis ANJLI2T (97.1 %) The G+C content of the genomic DNA was 44.4 mol%. The predominant respiratory quinone was menaquinone MK-7 and the major fatty acids were summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipid detected was phosphatidylethanolamine, while the minor polar lipids were various unidentified aminophospholipids, unidentified phospholipids and unidentified polar lipids. DNA and chemotaxonomic data supported the affiliation of strain Gsoil 032T to the genus Mucilaginibacter. Strain Gsoil 032T could be differentiated genotypically and phenotypically from recognized species of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter pocheonensis sp. nov. is proposed, with the type strain Gsoil 032T (=KCTC 12641T=LMG 23495T).