An Fnr-like protein encoded in Rhizobium leguminosarum biovar viciae shows structural and functional homology to Rhizobium meliloti FixK

1990 ◽  
Vol 223 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Sergio Colonna-Romano ◽  
Walter Arnold ◽  
Andreas Schlüter ◽  
Pierre Boistard ◽  
Alfred Pühler ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Functional Homology

Slow rehydration improves the recovery of dried bacterial populations

1992 ◽  
Vol 38 (6) ◽  
pp. 520-525 ◽  
Author(s):  
J. W. Kosanke ◽  
R. M. Osburn ◽  
G. I. Shuppe ◽  
R. S. Smith
Keyword(s):  
Relative Humidity ◽  
Rhizobium Leguminosarum ◽  
Moisture Absorption ◽  
Rhizobium Meliloti ◽  
Bacterial Populations ◽  
Bulk Powder ◽  
Alfalfa Seed ◽  
Powder Samples ◽  
Cellular Stresses ◽  
Rhizobium Leguminosarum Biovar Trifolii

Slow rehydration of bacteria from dried inoculant formulations provided higher viable counts than did rapid rehydration. Estimates were higher when clay and peat powder formulations of Rhizobium meliloti, Rhizobium leguminosarum biovar trifolii, and Pseudomonas putida, with water activities between 0.280 and 0.650, were slowly rehydrated to water activities of approximately 0.992 before continuing the dilution plating sequence. Rhizobium meliloti populations averaged 6.8 × 108 cfu/g and 1328 cfu/alfalfa seed greater when slowly rehydrated from bulk powder and preinoculated seeds, respectively. Bulk powder samples were slowly rehydrated to 0.992 water activity by the gradual addition of diluent, followed by a 10-min period for moisture equilibration. Preinoculated seed samples were placed in an environmental chamber at 24 °C with relative humidity greater than 80% for 1 h to allow moisture absorption. "Upshock," osmotic cellular stresses that occur during rehydration, was reduced when dried microbial formulations were slowly rehydrated and equilibrated before becoming fully hydrated in the dilution plating sequence. These procedures may also be applicable when estimating total viable bacterial populations from dried soil or other dry formulations. Key words: rehydration procedure, microbial rehydration, desiccation, Rhizobium, Pseudomonas.

Genetic characterization of Rhizobium sp. strain TAL1145 that nodulates tree legumes

1994 ◽  
Vol 40 (3) ◽  
pp. 208-215 ◽  
Author(s):  
M. L. C. George ◽  
J. P. W. Young ◽  
D. Borthakur
Keyword(s):  
Rhizobium Leguminosarum ◽  
Genetic Characterization ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Tree Legumes ◽  
Wide Range ◽  
The Common ◽  
Rrna Sequences ◽  
Rhizobium Sp

Rhizobium sp. strain TALI 145 nodulates Leucaena ieucocephaia and Phaseolus vulgaris, in addition to a wide range of tropical tree legumes. Six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. The common nod and nifA genes were situated approximately 17 kb apart, with the nodlJ genes in between. These clones enabled a derivative of TAL1145 carrying a partially deleted pSym to form ineffective nodules on both leucaena and bean, and a similar derivative of Rhizobium etli TAL182 to form ineffective nodules on bean. When two representative clones, pUHR9 and pUHR114, were each transferred to wild-type rhizobial strains, they allowed ineffective nodulation by Rhizobium meliloti on both leucaena and bean and by Rhizobium leguminosarum bv. viciae on bean. Transconjugants of R. leguminosarum bv. trifolii formed effective nodules on leucaena and ineffective nodules on bean. Tn5 mutagenesis of the symbiosis region resulted in a variety of nodulation and fixation phenotypes on leucaena and bean. On the basis of 16S rRNA sequences, TAL1145 was found to be distinct from both R. tropici and NGR234, the two groups of leucaena symbionts that were previously described.Key words: Rhizobium, Leucaena leucocephala, nodulation, nitrogen fixation.

Phylogenetic grouping and identification of Rhizobium isolates on the basis of random amplified polymorphic DNA profiles

1993 ◽  
Vol 39 (7) ◽  
pp. 665-673 ◽  
Author(s):  
John J. Dooley ◽  
Stephen P. Harrison ◽  
Lance R. Mytton ◽  
Malcolm Dye ◽  
Ann Cresswell ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Random Amplified Polymorphic Dna ◽  
Dna Amplification ◽  
Distinct Group ◽  
Principal Coordinate Analysis ◽  
The Other ◽  
Phylogenetic Grouping ◽  
Dna Profiles ◽  
Selection Of

Through the use of a single, random 15mer as a primer, between 1 and 12 DNA amplification products were obtained per strain from a selection of 84 Rhizobium and Bradyrhizobium isolates. A principal-coordinate analysis was used to analyse the resulting amplified DNA profiles and it was possible to assign isolates to specific groupings. Within the species Rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped together. Isolates of Rhizobium meliloti and Bradyrhizobium species formed their own clear, specific groups. Although it was possible to identify individual isolates on the basis of differences in their amplified DNA profiles, there was evidence that some amplified segments were conserved among individuals at the biovar and species levels.Key words: Rhizobium, DNA amplification, random primers.

scholarly journals Cloning, Sequencing, and Characterization of thecgmB Gene of Sinorhizobium meliloti Involved in Cyclic β-Glucan Biosynthesis

1999 ◽  
Vol 181 (15) ◽  
pp. 4576-4583 ◽  
Author(s):  
Ping Wang ◽  
Cheryl Ingram-Smith ◽  
Jill A. Hadley ◽  
Karen J. Miller
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Genomic Library ◽  
Rhizobium Meliloti ◽  
Functional Expression ◽  
Open Reading Frames ◽  
Inverse Pcr ◽  
Insertion Mutant ◽  
Overlapping Open Reading Frames ◽  
Reading Frames

ABSTRACT Periplasmic cyclic β-glucans of Rhizobium species provide important functions during plant infection and hypo-osmotic adaptation. In Sinorhizobium meliloti (also known asRhizobium meliloti), these molecules are highly modified with phosphoglycerol and succinyl substituents. We have previously identified an S. meliloti Tn5 insertion mutant, S9, which is specifically impaired in its ability to transfer phosphoglycerol substituents to the cyclic β-glucan backbone (M. W. Breedveld, J. A. Hadley, and K. J. Miller, J. Bacteriol. 177:6346–6351, 1995). In the present study, we have cloned, sequenced, and characterized this mutation at the molecular level. By using the Tn5 flanking sequences (amplified by inverse PCR) as a probe, an S. meliloti genomic library was screened, and two overlapping cosmid clones which functionally complement S9 were isolated. A 3.1-kb HindIII-EcoRI fragment found in both cosmids was shown to fully complement mutant S9. Furthermore, when a plasmid containing this 3.1-kb fragment was used to transformRhizobium leguminosarum bv. trifolii TA-1JH, a strain which normally synthesizes only neutral cyclic β-glucans, anionic glucans containing phosphoglycerol substituents were produced, consistent with the functional expression of an S. meliloti phosphoglycerol transferase gene. Sequence analysis revealed the presence of two major, overlapping open reading frames within the 3.1-kb fragment. Primer extension analysis revealed that one of these open reading frames, ORF1, was transcribed and its transcription was osmotically regulated. This novel locus of S. meliloti is designated thecgm (cyclic glucan modification) locus, and the product encoded by ORF1 is referred to as CgmB.

PCR as an ecological tool to determine the establishment and persistence of Rhizobium strains introduced into the field as seed inoculant Diane

1998 ◽  
Vol 49 (6) ◽  
pp. 923 ◽  
Author(s):  
M. Hebb ◽  
Alan E. Richardson ◽  
R. Reid ◽  
John Brockwell
Keyword(s):  
Rhizobium Leguminosarum ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Pcr Amplification ◽  
Field Trials ◽  
Rhizobium Strains ◽  
Inoculant Strain ◽  
Pcr Method ◽  
Polymerase Chain ◽  
Field Plots

Appraisal of the establishment and persistence of inoculant strains, and the diversity of the rhizobial populations in 2 field experiments, required the precise characterisation of isolates from individual nodules. The polymerase chain reaction (PCR) method of generating randomly amplified polymorphic DNA (RAPD) from simple bacterial cell lysates was applied to nodule isolates obtained from field plots of clover (Trifolium spp.) and medic (Medicago spp.) plants inoculated with Rhizobium leguminosarum bv. Trifolium and Rhizobium meliloti. Comparison of the PCR method with gel immune diffusion serology was applied to selected nodule isolates obtained from the clover trial. Agreement between the methods was high (97·6%). Further characterisation of nodule isolates from the 2 field trials proceeded using PCR amplification profiles only, which allowed a large number of isolates to be quickly and precisely identified. Mean recovery of inoculant strains in the first season of the clover trial was 76·5% across 10 hosts, and 45·3% in the second season sampling. Recovery of inoculant strains in the medic trial was assessed only during the second season of growth, which recorded a mean recovery of 53% across 8 hosts. In addition to providing a rapid and reliable means of identifying inoculant strains of R. leguminosarum bv. Trifolium and R. meliloti directly in association with a range of different host plants, the PCR approach also allowed inoculant strain types to be readily identified when recovered as isolates from plots in which they had not been introduced. Analysis of the non-inoculant strains by PCR also indicated that the naturalised populations of rhizobia at both sites were highly diverse.

Typing of Rhizobium by phages

1970 ◽  
Vol 16 (10) ◽  
pp. 1003-1009 ◽  
Author(s):  
Ryszard Staniewski
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Rhizobium Trifolii ◽  
Rhizobium Phaseoli ◽  
Group Iii ◽  
Phage Types ◽  
Group I ◽  
Rhizobium Lupini ◽  
Distinguished Group ◽  
Established Group

Two hundred and thirty strains of Rhizobium trifolii, Rhizobium leguminosarum for pea, vetch, horse bean, and Lathyrus spp., Rhizobium phaseoli and Rhizobium meliloti were subjected to phage typing. On the basis of their sensitivity to phages these strains were divided into three groups: I, II, and III.In group I, consisting of R. trifolii, R. leguminosarum for pea, vetch, and horse bean, and R. phaseoli, 18 phage types were established. Group II included some strains of R. trifolii and R. leguminosarum for pea and vetch. Among them three phage types were distinguished. Group III included R. meliloti strains and one strain of Rhizobium lupini for lupine. In that group 10 phage types were found.

Characterization of recA genes and recA mutants of Rhizobium meliloti and Rhizobium leguminosarum biovar viciae

1991 ◽  
Vol 229 (1) ◽  
pp. 86-95 ◽  
Author(s):  
Werner Selbitschka ◽  
Walter Arnold ◽  
Ursula B. Priefer ◽  
Thomas Rottschäfer ◽  
Michael Schmidt ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti

Formation and structure of root nodules induced on Macroptilium atropurpureum inoculated with various species of Rhizobium

1991 ◽  
Vol 69 (7) ◽  
pp. 1520-1532 ◽  
Author(s):  
Michael J. Trinick ◽  
Celia Miller ◽  
Paul A. Hadobas
Keyword(s):  
Rhizobium Leguminosarum ◽  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Matrix Material ◽  
Immunogold Labelling ◽  
Infection Threads ◽  
Glass Tubes ◽  
Infected Cells ◽  
Macroptilium Atropurpureum ◽  
Nodule Tissue

Fifteen strains of Rhizobium leguminosarum biovar trifolii formed ineffective nodules and (or) nodule-like structures (rhizobia were re-isolated from both structures) on Macroptilium atropurpureum grown in enclosed glass tubes. Bacteria were observed among the parenchyma cells surrounding the nodule-like structures. One variant of R. leguminosarum biovar trifolii (NGR66/ST) isolated from M. atropurpureum formed nodules on this host that exhibited abnormal intercellular and intracellular infection. The bacteria (NGR66/ST) were contained within threadlike structures, surrounded by matrix material. The identities of the Rhizobium strains were confirmed serologically after reisolation and in sections of nodule tissue using immunogold labelling. Rhizobium leguminosarum biovar phaseoli strain NGR76 isolated from Phaseolus vulgaris formed nodules on M. atropurpureum resembling those formed by effective Bradyrhizobium strains. The association was partially effective in nitrogen fixation, and this was reflected in the nodule structure. The percentage of cells infected was lower than that in fully effective nodules. There was a high frequency of infected cells showing degeneration; these were located throughout the nodule tissue and were often adjacent to healthy infected cells. The rhizobia appeared to infect new nodule cells via infection threads, which were abundant both intercellularly and intracellularly in young, mature, and degenerating host nodule cells. Strains of R. leguminosarum biovar viceae and Rhizobium meliloti were unable to induce nodule-like structures on M. atropurpureum. Key words: Macroptilium, Bradyrhizobium, Rhizobium, microscopy, nodule, structure.

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