title: Bradyrhizobium pachyrhizi sp. nov. and Bradyrhizobium jicamae sp. nov., isolated from effective nodules of Pachyrhizus erosus.
abstract: Several strains isolated from the legume Pachyrhizus erosus were characterized on the basis of diverse genetic, phenotypic and symbiotic approaches. These novel strains formed two groups closely related to Bradyrhizobium elkanii according to their 16S rRNA gene sequences. Strains PAC48T and PAC68T, designated as the type strains of these two groups, presented 99.8 and 99.1% similarity, respectively, in their 16S rRNA gene sequences with respect to B. elkanii USDA 76T. In spite of these high similarity values, the analysis of additional phylogenetic markers such as atpD and glnII genes and the 16S-23S intergenic spacer (ITS) showed that strains PAC48T and PAC68T represented two separate novel species of the genus Bradyrhizobium with B. elkanii as their closest relative. Phenotypic differences among the novel strains isolated from Pachyrhizus and B. elkanii were found regarding the assimilation of carbon sources and antibiotic resistance. All these differences were congruent with DNA-DNA hybridization analysis which revealed 21% genetic relatedness between strains PAC48T and PAC68T and 46% and 25%, respectively, between these strains and B. elkanii LMG 6134T. The nodD and nifH genes of strains PAC48T and PAC68T were phylogenetically divergent from those of bradyrhizobia species that nodulate soybean. Soybean was not nodulated by the novel Pachyrhizus isolates. Based on the genotypic and phenotypic data obtained in this study, the new strains represent two novel species for which the names Bradyrhizobium pachyrhizi sp. nov. (type strain PAC48T=LMG 24246T=CECT 7396T) and Bradyrhizobium jicamae sp. nov. (type strain PAC68T=LMG 24556T=CECT 7395T) are proposed.
authors: Departamento de Microbiología y Genética, Universidad de Salamanca, Spain.
authors: Martha Helena
authors: MH
authors: Ramírez-Bahena
authors: Alvaro
authors: A
authors: Peix
authors: Raúl
authors: R
authors: Rivas
authors: María
authors: M
authors: Camacho
authors: Dulce N
authors: DN
authors: Rodríguez-Navarro
authors: Pedro F
authors: PF
authors: Mateos
authors: Eustoquio
authors: E
authors: Martínez-Molina
authors: Anne
authors: A
authors: Willems
authors: Encarna
authors: E
authors: Velázquez
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D020369:Bradyrhizobium / Q000145:classification* / Q000302:isolation & purification*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D029905:Pachyrhizus / Q000382:microbiology*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S