Daejeonia ginsenosidivorans gen. nov., sp. nov., a ginsenoside-transforming bacterium isolated from lake water.

Abstract

A Gram-stain-negative, oxidase- and catalase-positive, strictly aerobic, non-gliding bacterial strain, designated as NPT, was isolated from lake water and subjected to a taxonomic study using a polyphasic approach. Colonies of strain NP5T were light-yellow-coloured, circular with regular margins, and opaque. Cells were rods, 0.2-0.5 µm wide and 1.2-3.0 µm long. Strain NP5T possessed β-glycosidase activity, which was responsible for its ability to convert ginsenosides Rb1, Rc and Rd (three main active components of ginseng) to ginsenoside F2. Phylogenetic study based on the 16S rRNA gene sequence put strain NP5T in a distinct lineage in the family Flavobacteriaceae, sharing less than 96.0 % sequence similarity with members of the closely related genera Chryseobacterium, Bergeyella, Epilithonimonas and 'Candidatus Amoebinatus'. The novel isolate showed the highest sequence similarity with the genus Chryseobacterium. Strain NP5T contained MK-6 as predominant quinone, and iso-C15 : 0, iso-C17 : 0 3-OH, iso-C16 : 0 3-OH, C18 : 0 3-OH, anteiso-C15 : 0 and C16 : 1ω7c and/or C16 : 1ω6c (summed feature 3) as major fatty acids. The DNA G+C content was 44.8 mol%. The main polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The physiological, biochemical and taxonomical characteristics allowed the phenotypic differentiation of strain NP5T from its closest phylogenetic neighbours. On the basis of the evidence of this polyphasic study, isolate NP5T represents a novel genus and species in the family Flavobacteriaceae for which the name Daejeonia ginsenosidivorans gen. nov., sp. nov. is proposed. The type strain is NP5T (=KACC 18626T=LMG 29198T).