Flavobacterium kyungheensis sp. nov., isolated from soil of a ginseng field

A Gram-staining negative, strictly aerobic, motile by gliding, non-spore-forming, pale yellow pigmented and rod-shaped bacterium designated strain THG-107^T was isolated from soil of a ginseng field on Ganghwa Island in the Republic of Korea and its taxonomic position was investigated by using a polyphasic study. Growth of strain THG-107^T was found to occur at 4–37 °C (optimum, 20–30 °C), at pH 5.5–10 (optimum, pH 7.0) and in the presence of 0–1 % (w/v) NaCl (optimum, absence) on R2A agar. On the basis of 16S rRNA gene sequence similarity, strain THG-107^T was shown to belong to the family Flavobacteriaceae and was related to Flavobacterium denitrificans ED5^T (99.1 % similarity). The G+C content of the genomic DNA was determined to be 34.2 mol%. These results are consistent with characteristics of members of the genus Flavobacterium. The only isoprenoid quinone detected in strain THG-107^T was menaquinone-6 (MK-6) and the major polyamine was identified as homospermidine (82.9 %). The major polar lipid detected was phosphatidylethanolamine and the major cellular fatty acids were identified as iso-C_15:0 (26.3 %), iso-C_17:0 3OH (12.6 %) and summed feature 3 (comprising C_16:1 ω7c and/or C_16:1 ω6c; 11.6 %). Flexirubin-type pigments were found to be present. Strain THG-107^T has β-glucosidase activity to convert ginsenosides Rb₁ and Rd into Gyp17 and F₂. DNA-DNA hybridization with F. denitrificans ED5^T was 52 %. Strain THG-107^T could be distinguished from F. denitrificans ED5^T and the other species of the genus Flavobacterium by its phylogenetic and genetic distinctiveness and by several phenotypic properties. Therefore, strain THG-107^T is considered to represent a novel species in the genus Flavobacterium, for which the name Flavobacterium kyungheensis sp. nov. is proposed (type strain THG-107^T = KACC 16219^T = LMG 26575^T).