Rhizobium multihospitium sp. nov., isolated from multiple legume species native of Xinjiang, China

Abstract

Thirty-one rhizobial strains isolated from nodules of legumes native of Xinjiang, China, were characterized. These strains were classified as belonging to the genus Rhizobium based on amplified 16S rDNA restriction analysis (ARDRA). The strains were distinguished from recognized Rhizobium species using analysis of 16S-23S rDNA intergenic spacers (IGS-RFLP), SDS-PAGE analysis of whole proteins and BOX-PCR; the test strains always formed a distinct cluster with patterns that were quite different from those of the reference rhizobial strains used. According to the phylogenetic analysis based on the 16S rRNA gene, the test strains belonged to the genus Rhizobium, with Rhizobium tropici, Rhizobium rhizogenes and Rhizobium lusitanum as the closest related species, with 99.6, 99.2 and 99.4 % sequence similarities, respectively, between the type strains of the three Rhizobium species and strain CCBAU 83401T .Phylogenetic analyses of the representative strains using IGS and atpD, recA and glnII genes all confirmed the phylogenetic arrangements obtained using the 16S rRNA gene. The DNA-DNA relatedness values between strain CCBAU 83401 T and strains CCBAU 83364, CCBAU 83345and CCBAU 83523 ranged from 80.8 to 100 %, showing that they belong to the same species. The DNA-DNA relatedness between strain CCBAU 83401 T and R. tropici IIB CIAT 899 T , R. tropici IIA CFN 299, R. rhizogenes LMG 150 T and R. lusitanum P1-7 T were 26.9, 27.7, 38.2 and 22.6 %, respectively, clearly indicating that strain CCBAU 83401 T represents a novel species.Phenotypic characterization of four representative strains, CCBAU 83401 T , CCBAU 83364, CCBAU 83345 and CCBAU 83523, showed several distinctive features that differentiated them from closely related species. The 31 strains had identical nodD and nifH genes, which were very similar to those of the bean-nodulating R. lusitanum, Devosia neptuniae and R. tropici IIB. Based upon these results, the strains from this study are considered to represent a novel species, for which the name Rhizobium multihospitium sp. nov. is proposed. The DNA G+C content ranged from 65.3 to 66.0 mol% (T m ). The type strain is CCBAU 83401 T (5LMG 23946 T 5HAMBI 2975 T ), which nodulates Robinia pseudoacacia, but not Leucaena leucocephala, Phaseolus vulgaris, Pisum sativum or Medicago sativa.

Rhizobium freirei sp. nov., a symbiont of Phaseolus vulgaris that is very effective at fixing nitrogen

“…We tested whether the similarity between PRF 81 T and R. multihospitium also included other parts of the ribosomal (rrn) operon by comparing the sequences of their 16S-23S intergenic spacer (IGS) regions. The available IGS sequences of four R. multihospitium strains were identical to each other (Han et al, 2008), as were the sequences of the three rrn operons in the PRF 81 T genome (Ormeño-Orrillo et al, 2012). Interestingly, the PRF 81 T and R. multihospitium IGS sequences were only 76.4 % identical ( Table S1), indicating that they may have recombined at their 16S rRNA gene loci at some point in their evolutionary history.…”

Rhizobium borbori sp. nov., aniline-degrading bacteria isolated from activated sludge

“…After a series of taxonomic changes that have been proposed since the 1980s, the genus Rhizobium consists of 43 species at the time of writing, including the recently described species Rhizobium selenitireducens (Hunter et al, 2007), R. pisi (Ramírez-Bahena et al, 2008), R. oryzae (Peng et al, 2008), R. multihospitium (Han et al, 2008), R. miluonense (Gu et al, 2008), R. alamii (Berge et al, 2009), R. alkalisoli (Lu et al, 2009), R. mesosinicum (Lin et al, 2009) and R. tibeticum (Hou et al, 2009). Most of them have been isolated from nodules of leguminous plants or the roots of cereals as symbiotic or associated nitrogen-fixation partners, with the exception of the selenite-reducing R. selenitireducens, exopolysaccharide-producing R. alamii, polysaccharide-hydrolysing Rhizobium cellulosilyticum and cyanide-degrading Rhizobium daejeonense (Berge et al, 2009;García-Fraile et al, 2007;Hunter et al, 2007;Quan et al, 2005).…”

The Symbiotic Efficiency of Legume Tree Rhizobia for Host Range Legumes in Central Saudi Arabia

“…Similar results were reported by Mahmood and Akthar (2008) when Vigna mungo was successfully cross-inoculated with the Rhizobium isolates from tree legumes. The Rhizobium isolates species that failed to nodulate in those acacias might be explained by the loss of a symbiotic plasmid (sym plasmid) or a lateral gene transfer or changes in the host specific nod gene (Haukka et al, 1996;Kucuk et al, 2006;Han et al, 2008). Environmental conditions, especially water deficiency, may play a crucial role in nodulation and may be responsible for some non-specific nodulation (Ben Ramdhane et al, 2009;Fitouri et al, 2012).…”