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A Gram-positive, aerobic, nonmotile strain, NM2E3(T) was identified as Brevibacterium based on the 16S rRNA gene sequence analysis and had the highest similarities to Brevibacterium jeotgali SJ5-8(T) (97.3 %). This novel bacterium was isolated from root tissue of Prosopis laegivata grown at the edge of a mine tailing in San Luis Potosí, Mexico. Its cells were non-spore-forming rods, showing catalase and oxidase activities and were able to grow in LB medium added with 40 mM Cu(2+), 72 mM As(5+) and various other toxic elements. Anteiso-C15:0 (41.6 %), anteiso-C17:0 (30 %) and iso-C15:0 (9.5 %) were the major fatty acids. MK-8(H2) (88.4 %) and MK-7(H2) (11.6 %) were the major menaquinones. The DNA G + C content of the strain NM2E3(T) was 70.8 mol % (Tm). DNA-DNA hybridization showed that the strain NM2E3(T) had 39.8, 21.7 and 20.3 % relatedness with B. yomogidense JCM 17779(T), B. jeotgali JCM 18571(T) and B. salitolerans TRM 45(T), respectively. Based on the phenotypic and genotypic analyses, the strain NM2E3(T) (=CCBAU 101093(T) = HAMBI 3627(T) = LMG 8673(T)) is reported as a novel species of the genus Brevibacterium, for which the name Brevibacterium metallicus sp. nov., is proposed.

Five bacterial strains representing 45 isolates originated from root nodules of the medicinal legume Sophora flavescens were defined as two novel groups in the genus Rhizobium based on their phylogenetic relationships estimated from 16S rRNA genes and the housekeeping genes recA, glnII and atpD. These groups were distantly related to Rhizobium leguminosarum USDA 2370(T) (95.6 % similarity for group I) and Rhizobium phaseoli ATCC 14482(T) (93.4 % similarity for group II) in multilocus sequence analysis. In DNA-DNA hybridization experiments, the reference strains CCBAU 03386(T) (group I) and CCBAU 03470(T) (group II) showed levels of relatedness of 17.9-57.8 and 11.0-42.9 %, respectively, with the type strains of related species. Both strains CCBAU 03386(T) and CCBAU 03470(T) contained ubiquinone 10 (Q-10) as the major respiratory quinone and possessed 16 : 0, 18 : 0, 19 : 0 cyclo ω8c, summed feature 8 and summed feature 2 as major fatty acids, but did not contain 20 : 3 ω6,8,12c. Phenotypic features distinguishing both groups from all closely related species of the genus Rhizobium were found. Therefore, two novel species, Rhizobium sophorae sp. nov. for group I (type strain CCBAU 03386(T) = E5(T) = LMG 27901(T) = HAMBI 3615(T)) and Rhizobium sophoriradicis sp. nov. for group II (type strain CCBAU 03470(T) = C-5-1(T) = LMG 27898(T) = HAMBI 3510(T)), are proposed. Both groups were able to nodulate Phaseolus vulgaris and their hosts of origin (Sophora flavescens) effectively and their nodulation gene nodC was phylogenetically located in the symbiovar phaseoli., (© 2015 IUMS.)

Two novel Gram-stain-negative strains (CCBAU 03422(T) and CCBAU 03415) isolated from root nodules of Sophora flavescens were classified phylogenetically into the genus Phyllobacterium based on the comparative analysis of 16S rRNA and atpD genes. They showed 99.8 % rRNA gene sequence similarities to Phyllobacterium brassicacearum LMG 22836(T), and strain CCBAU 03422(T) showed 91.2 and 88.6 % atpD gene sequence similarities to strains Phyllobacterium endophyticum LMG 26470(T) and Phyllobacterium brassicacearum LMG 22836(T), respectively. Strain CCBAU 03422(T) contained Q-10 as its major quinone and showed a cellular fatty acid profile, carbon source utilization and other phenotypic characteristics differing from type strains of related species. DNA-DNA relatedness (lower than 48.8 %) further confirmed the differences between the novel strains and the type strains of related species. Strain CCBAU 03422(T) could nodulate and fix nitrogen effectively on its original host plant, Sophora flavescens. Based upon the results mentioned above, a novel species named Phyllobacterium sophorae is proposed and the type strain is CCBAU 03422(T) ( = A-6-3(T) = LMG 27899(T) = HAMBI 3508(T))., (© 2015 IUMS.)

The nodulation of Erythrophleum fordii has been recorded recently, but its microsymbionts have never been studied. To investigate the diversity and biogeography of rhizobia associated with this leguminous evergreen tree, root nodules were collected from the southern subtropical region of China. A total of 166 bacterial isolates were obtained from the nodules and characterized. In a PCR-based restriction fragment length polymorphism (RFLP) analysis of ribosomal intergenic sequences, the isolates were classified into 22 types within the genus Bradyrhizobium. Sequence analysis of 16S rRNA, ribosomal intergenic spacer (IGS), and the housekeeping genes recA and glnII classified the isolates into four groups: the Bradyrhizobium elkanii and Bradyrhizobium pachyrhizi groups, comprising the dominant symbionts, Bradyrhizobium yuanmingense, and an unclassified group comprising the minor symbionts. The nodC and nifH phylogenetic trees defined five or six lineages among the isolates, which was largely consistent with the definition of genomic species. The phylogenetic results and evolutionary analysis demonstrated that mutation and vertical transmission of genes were the principal processes for the divergent evolution of Bradyrhizobium species associated with E. fordii, while lateral transfer and recombination of housekeeping and symbiotic genes were rare. The distribution of the dominant rhizobial populations was affected by soil pH and effective phosphorus. This is the first report to characterize E. fordii rhizobia., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Three slow-growing rhizobial strains, designated RITF806(T), RITF807 and RITF211, isolated from root nodules of Acacia melanoxylon grown in Ganzhou city, Jiangxi Province, China, had been previously defined, based on amplified 16S rRNA gene restriction analysis, as a novel group within the genus Bradyrhizobium. To clarify their taxonomic position, these strains were further analysed and compared with reference strains of related bacteria using a polyphasic approach. According to 16S rRNA gene sequence analysis, the isolates formed a group that was closely related to 'Bradyrhizobium rifense' CTAW71, with a similarity value of 99.9%. In phylogenetic analyses of the housekeeping and symbiotic gene sequences, the three strains formed a distinct lineage within the genus Bradyrhizobium, which was consistent with the results of DNA-DNA hybridization. In analyses of cellular fatty acids and phenotypic features, some differences were found between the novel group and related species of the genus Bradyrhizobium, indicating that these three strains constituted a novel group distinct from any recognized species of the genus Bradyrhizobium. Based on the data obtained in this study, we conclude that our strains represent a novel species of the genus Bradyrhizobium, for which the name Bradyrhizobium ganzhouense sp. nov. is proposed, with RITF806(T) ( = CCBAU 101088(T) = JCM 19881(T)) as the type strain. The DNA G+C content of strain RITF806(T) is 64.6 mol% (T(m))., (© 2014 IUMS.)

In a survey of the biodiversity and biogeography of rhizobia associated with soybean (Glycine max L.) in different sites of the Northern (Huang-Huai-Hai) Plain of China, ten strains were defined as representing a novel genomic species in the genus of Bradyrhizobium. They were distinguished from defined species in restriction fragment length polymorphism (RFLP) analysis of the 16S rRNA gene and the 16S-23S rRNA gene intergenic spacer (IGS). In BOX-PCR, these strains presented two patterns that shared 94% similarity, demonstrating that they were a homogenous group with limited diversity. In phylogenetic analyses of the 16S rRNA gene, IGS and housekeeping gene sequences, four representative strains formed a distant lineage within the genus Bradyrhizobium, which was consistent with the results of DNA-DNA hybridization. The strains of this novel group formed effective nodules with G. max, Glycine soja and Vigna unguiculata in cross-nodulation tests and harboured symbiotic genes (nodC and nifH) identical to those of reference strains of Bradyrhizobium japonicum, Bradyrhizobium liaoningense and 'Bradyrhizobium daqingense' originating from soybean, implying that the novel group may have obtained these symbiotic genes by lateral gene transfer. In analyses of cellular fatty acids and phenotypic features, some differences were found between the novel group and related Bradyrhizobium species, demonstrating that the novel group is distinct phenotypically from other Bradyrhizobium species. Based upon the data obtained, these strains are proposed to represent a novel species, Bradyrhizobium huanghuaihaiense sp. nov., with CCBAU 23303(T) ( = LMG 26136(T)  = CGMCC 1.10948(T)  = HAMBI 3180(T)) as the type strain. The DNA G+C content of strain CCBAU 23303(T) is 61.5 mol% (T(m)).

Seven Rhizobium strains associated with various legume species grown in different geographical regions of China were defined into four genomic groups related to Rhizobium giardinii, based upon ribosomal intergenic spacer RFLP, phylogenies of 16S rRNA and housekeeping (atpD, recA and glnII) genes, and DNA relatedness. Three strains in group I were classified as R. giardinii, as they showed high gene sequence similarities (>97 %) and DNA relatedness (64.3-67.5 %) to R. giardinii H152(T). Groups II, III and IV differed from all defined Rhizobium species based upon the consensus of all analyses. As group II contained two strains that originated from two distinct populations, we propose this group as a novel species, Rhizobium herbae sp. nov., with strain CCBAU 83011(T) ( = LMG 25718(T) = HAMBI 3117(T)) as the type strain.

Seventeen strains of lespedeza rhizobia, a previously defined novel group, were further characterized by comparison with phylogenetically related species using a polyphasic approach, including SDS-PAGE of whole-cell proteins, PCR-based restriction fragment length polymorphism analysis of ribosomal intergenic spacer sequences, determination of DNA G+C contents, DNA-DNA hybridization and analysis of phenotypic features. Based on data obtained in the present and previous studies, a novel species, Rhizobium miluonense sp. nov., is proposed for these strains. The type strain of R. miluonense is CCBAU 41251(T) (=LMG 24208(T)=HAMBI 2971(T)). Strain CCBAU 41251(T) could form ineffective nodules on Phaseolus vulgaris in addition to its original host Lespedeza chinensis.

Caragana species are woody legumes widely distributed in the arid regions of China. These plants form root nodules but their nodule bacteria have not been clearly classified. A total of 112 symbiotic bacterial isolates were obtained from four Caragana species grown in Liaoning Province and were characterized with ARDRA, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins, BOX-PCR and sequencing of the 16S rRNA gene. Most of them were classified as Mesorhizobium belonging to 11 putative species. Three isolates were identified as Rhizobium etli and Burkholderia spp. This study offers new information about the Caragana-rhizobia association and resource for selection of inoculants used in sustainable agriculture and for further studies on the Caragana rhizobia.