Mesorhizobium hankyongi sp. nov. Isolated from Soil of Ginseng Cultivating Field.

A Gram-negative, non-spore-forming and rod-shaped, bacterium (designated Gsoil 531) was isolated from soil of a ginseng field. On the basis of 16S rRNA gene sequence, strain Gsoil 531 clustered with species of the genus Mesorhizobium and was closely related to M. camelthorni CCNWXJ 40-4 (98.9%) and M. alhagi CCNWXJ12-2 (98.7%). The DNA G + C content was 62.9 mol% and the predominant quinone was ubiquinone-10 (Q-10). The major cellular fatty acids were C, C cyclo ω8c and summed feature 8 (C ω7c/C ω6c). The DNA-DNA hybridization values were less than 35.0% between novel isolate and its closest reference strains M. camelthorni HAMBI 3020, M. alhagi HAMBI 3019 and M tamadayense LMG 26736. Physiological, biochemical and low values of DNA-DNA hybridization results enabled strain Gsoil 531 to be differentiated genotypically and phenotypically from all known species of the genus Mesorhizobium. Therefore, strain Gsoil 531 signifies a novel species of the genus Mesorhizobium, for which the name Mesorhizobium hankyongi sp. nov. is proposed. The type strain Gsoil 531 (= KACC 19443 = LMG 30463).