Proposal of three novel species of soil bacteria, Variovorax ureilyticus, Variovorax rhizosphaerae, and Variovorax robiniae, in the family Comamonadaceae.

Three novel bacterial strains (UCM-2, UCM-G28, and UCM-G35) were obtained while isolating soil bacteria for the development of antibiotics. Cells of these strains were Gram-negative, non-spore forming, motile by means of a single flagellum, and rod shaped. In all strains, the predominant isoprenoid quinone was ubiquinone-8 (Q-8). Cells contained C, summed feature 3 (Cω7c and/or Cω6c), summed feature 8 (Cω7c and/or Cω6c), and C cyclo as the major fatty acids, and C 3-OH as the major hydroxy fatty acid. The polar lipid profiles of the three novel strains were dominated by diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. The genomic DNA G + C contents of strains UCM-2, UCM-G28, and UCMG35 were 67.5, 65.9, and 66.4 mol%, respectively. Phylogenetic analyses based on 16S rRNA sequences showed that strain UCM-2 was most closely related to Variovorax soli NBRC 106424, whereas strains UCM-G28 and UCM-G35 were most similar to Variovorax ginsengisoli Gsoil 3165. Values indicating DNA-DNA hybridization between the novel isolates and closely related species in the genus Variovorax were lower than the 70% cut-off point. These phenotypic, chemotaxonomic, and phylogenetic data indicate that the three isolates should be classified as new members of the genus Variovorax, for which the names Variovorax ureilyticus sp. nov., Variovorax rhizosphaerae sp. nov., and Variovorax robiniae sp. nov. are proposed. The type strains are UCM-2 (= KACC 18899 = NBRC 112306), UCMG28 (= KACC 18900 = NBRC 112307), and UCM-G35 (= KACC 18901 = NBRC 112308), respectively.