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

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.

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.

scholarly journals Cloning and characterization of the katA gene of Rhizobium meliloti encoding a hydrogen peroxide-inducible catalase.

1996 ◽  
Vol 178 (23) ◽  
pp. 6802-6809 ◽  
Author(s):  
D Hérouart ◽  
S Sigaud ◽  
S Moreau ◽  
P Frendo ◽  
D Touati ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rhizobium Meliloti

scholarly journals Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in Rhizobium leguminosarum PRE

1988 ◽  
Vol 54 (12) ◽  
pp. 3008-3013 ◽  
Author(s):  
René M. Klein Lankhorst ◽  
Panagiotis Katinakis ◽  
Albert van Kammen ◽  
Rommert C. van den Bos
Keyword(s):  
Rhizobium Leguminosarum ◽  
Identification And Characterization ◽  
Dehydrogenase Complex

scholarly journals Chemical characterization of effective and ineffective strains of Rhizobium leguminosarum bv. viciae.

1999 ◽  
Vol 46 (4) ◽  
pp. 1001-1009
Author(s):  
S F Izmailov ◽  
G Y Zhiznevskaya ◽  
L V Kosenko ◽  
G N Troitskaya ◽  
N N Kudryavtseva ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Rhizobium Leguminosarum ◽  
Unsaturated Fatty Acids ◽  
Effective Strain ◽  
Chemical Characterization ◽  
Unsaturation Index ◽  
Fa Composition ◽  
Sds Page ◽  
Lower Molecular Mass

Chemical composition of lipopolysaccharide (LPS) isolated from an effective (97) and ineffective (87) strains of R. l. viciae has been determined. LPS preparations from the two strains contained: glucose, galactose, mannose, fucose, arabinose, heptose, glucosamine, galactosamine, quinovosamine, and 3-N-methyl-3,6-dideoxyhexose, as well as glucuronic, galacturonic and 3-deoxyoctulosonic acid. The following fatty acids were identified: 3-OH 14:0, 3-OH 15:0, 3-OH 16:0, 3-OH 18:0 and 27-OH 28:0. The ratio of 3-OH 14:0 to other major fatty acids in LPS 87 was higher that in LPS 97. SDS/PAGE profiles of LPS indicated that, in lipopolysaccharides, relative content of S form LPS I to that of lower molecular mass (LPS II) was much higher in the effective strain 97 than in 87. All types of polysaccharides exo-, capsular-, lipo, (EPS, CPS, LPS, respectively) examined possessed the ability to bind faba bean lectin. The degree of affinity of the host lectin to LPS 87 was half that to LPS 97. Fatty acids (FA) composition from bacteroids and peribacteroid membrane (PBM) was determined. Palmitic, stearic and hexadecenoic acids were common components found in both strains. There was a high content of unsaturated fatty acids in bacteroids as well as in PBM lipids. The unsaturation index in the PBM formed by strain 87 was lower than in the case of strain 97. Higher ratio of 16:0 to 18:1 fatty acids was characteristic for PMB of the ineffective strain.

scholarly journals Regulation and characterization of mutants of fixABCX in Rhizobium leguminosarum.

2021 ◽  
Author(s):  
Isabel Webb ◽  
Jiabao Xu ◽  
Carmen Sanchez-Cañizares ◽  
Ramakrishnan Karunakaran ◽  
Vinoy Ramachandran ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Redox Balance ◽  
Rna Seq ◽  
Wild Type ◽  
Transcription Start Sites ◽  
Sym Plasmid ◽  
Microaerobic Conditions ◽  
Type Infection

Symbiosis between Rhizobium leguminosarum and Pisum sativum requires tight control of redox balance in order to maintain respiration under the microaerobic conditions required for nitrogenase, whilst still producing the eight electrons and sixteen molecules of ATP needed for nitrogen fixation. FixABCX, electron transfer flavoproteins essential for nitrogen fixation, are encoded on the Sym plasmid (pRL10), immediately upstream of nifA, which encodes the general transcriptional regulator of nitrogen fixation. There is a symbiotically-regulated NifA-dependent promoter upstream of fixA (PnifA1), as well as an additional basal constitutive promoter driving background expression of nifA (PnifA2). These were confirmed by 5’-end mapping of transcription start sites using differential (d) RNA-seq. Complementation of polar fixAB and fixX mutants (Fix- strains) confirmed expression of nifA from PnifA1 in symbiosis. Electron microscopy combined with single-cell Raman microspectroscopy characterization of fixAB mutants revealed previously unknown heterogeneity in bacteroid morphology within a single nodule. Two morphotypes of mutant fixAB bacteroids were observed. One was larger than wild-type bacteroids and contained high levels of polyhydroxy-3-butyrate, a complex energy/reductant storage product. A second bacteroid phenotype was morphologically and compositionally different and resembled wild-type infection thread cells. From these two characteristic fixAB mutant bacteroid morphotypes, inferences can be drawn on the metabolism of wild-type nitrogen-fixing bacteroids.

Characterization of Symbiotic Genes and Regulation of Their Expression in Rhizobium Leguminosarum PRE

1987 ◽  
pp. 241-243 ◽  
Author(s):  
Jan Hontelez ◽  
Rene Klein Lankhorst ◽  
Jan-Dirk Jansma ◽  
Evert Jacobsen ◽  
Rommert C. van den Bos ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Symbiotic Genes

scholarly journals Bio-chemical characterization of rhizobia isolated from root nodules of Velvet bean (Mucuna pruriens L.)

Our Nature ◽  
2017 ◽  
Vol 15 (1-2) ◽  
pp. 7-12 ◽  
Author(s):  
Som Prasad Paudyal ◽  
Vimal NP Gupta
Keyword(s):  
Rhizobium Meliloti ◽  
Root Nodules ◽  
Chemical Characterization ◽  
High Sensitivity ◽  
Mucuna Pruriens ◽  
Velvet Bean ◽  
Trigonella Foenum Graecum ◽  
Antibiotics Sensitivity ◽  
The Himalaya

Rhizobia are the symbiotic bacteria found in the soil which have potential ability to convert atmospheric di-nitrogen into usable form. A total of ten rhizobial strains were isolated from the root nodules of a medicinal legume Mucuna pruriens (L.) that commonly grow in the foothills of the Himalaya. All the ten   strains isolated from different locations of same area were morphologically, biochemically and physiologically characterized based on the Bergey’s Manual of systematic Bacteriology. They were tested for the antibiotics sensitivity. The isolates showed high sensitivity to amoxicillin and least to erythromycin. Authentication test was done in eleven legumes but shown nodulations only in Trigonella foenum-graecum, Mucuna pruriens and Medicago sativa. The morphology, physiology, biochemical and infection test studies carried out justifies that the bacteria isolated belonged to the species of Rhizobium meliloti.

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