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Rhizobium panacihumi sp. nov., an isolate from ginseng-cultivated soil, as a potential plant growth promoting bacterium

Kang, Jong-Pyo, Huo, Yue, Kim, Yeon-Ju, Ahn, Jong-Chan, Hurh, Joon, Yang, Dong-Uk, Yang, Deok-Chun
Archives of microbiology 2019 v.201 no.1 pp. 99-105
DNA, Rhizobium, enzymes, essential genes, fatty acids, flagellum, indole acetic acid, new species, phosphates, phosphatidylethanolamines, plant growth-promoting rhizobacteria, ribosomal RNA, sequence homology, siderophores, soil, South Korea
A novel bacterial strain designated DCY116ᵀ was isolated from ginseng-cultivated soil in Gochang-gun, Republic of Korea. Strain DCY116ᵀ, belongs to the genus Rhizobium, and is closely related to Rhizobium yantingense H66ᵀ (98.3%), Neorhizobium huautlense S02ᵀ (98.2%), Rhizobium soli DS-42ᵀ (98.1%), Rhizobium smilacinae PTYR-5ᵀ (97.9%), and Neorhizobium alkalisoli CCBAU 01393ᵀ (97.9%) based on 16S rRNA gene sequence analysis. Analysis of the housekeeping genes atpD, recA, and glnII showed low levels of sequence similarity (96.8%) between strain DCY116ᵀ and other closely related species. Strain DCY116ᵀ was Gram-stain negative, motile by peritrichous flagella, rod-shaped, strictly aerobic, catalase- and oxidase-positive. Q-10 was the predominant ubiquinone. The major cellular fatty acids were identified as C₁₆:₀ and summed feature 8 (C₁₈:₁ ω7c and/or C₁₈:₁ ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and an unknown lipid (L1-3). Genomic DNA G + C content of strain DCY116ᵀ was determined to be 57.2 mol%. DNA–DNA homology values between strain DCY116ᵀ and closely related species of the genus Rhizobium were lower than 40%. Strain DCY116ᵀ produced indole-3-acetic acid, siderophores, and was able to solubilize phosphate as a potential plant growth promoting bacterium. In conclusion, the results of this study support strain DCY116ᵀ as a novel species of the genus Rhizobium, for which the name Rhizobium panacihumi is proposed. The type strain is DCY116ᵀ (= KCTC 62017ᵀ = JCM 32251ᵀ).