Mutations conferring acid sensitivity in the acid-tolerant strains Rhizobium meliloti WSM419 and Rhizobium leguminosarum biovar viciae WSM710

@article{Tiwari1992MutationsCA,
  title={Mutations conferring acid sensitivity in the acid-tolerant strains Rhizobium meliloti WSM419 and Rhizobium leguminosarum biovar viciae WSM710},
  author={R. Tiwari and W. Reeve and A. R. Gleenn},
  journal={Fems Microbiology Letters},
  year={1992},
  volume={100},
  pages={107-112}
}
The genetic basis of acid-tolerance in rhizobia is being investigated by the isolation and molecular characterisation of Tn5-induced acid-sensitive mutants. Strains of Rhizobium meliloti (the most acid-sensitive species of rhizobia) respond to increasing concentrations of calcium in the growth medium both by growing faster and by being able to grow at progressively lower pH. Two classes of acid-sensitive mutant of R. meliloti WSM419 (a relatively acid-tolerant inoculant strain) have been… Expand
Acid tolerance in Rhizobium meliloti strain WSM419 involves a two-component sensor-regulator system.
TLDR
Data implicate a two-component sensor-regulator protein pair in acid tolerance in R. meliloti and suggest their involvement in pH sensing and/or response by these bacteria. Expand
Regulation of exopolysaccharide production in Rhizobium leguminosarum biovar viciae WSM710 involves exoR.
TLDR
The data suggest that Tn5 has disrupted a regulatory gene encoding a protein that negatively modulates EPS biosynthesis in R. leguminosarum bv. Expand
A histidine kinase sensor protein gene is necessary for induction of low pH tolerance in Sinorhizobium sp. strain BL3
TLDR
It was shown that actX was induced at low pH and the method of gene identification used in this study for isolation of actX may be applied for the isolation of other genes involved in tolerance to adverse environmental factors. Expand
Isolation and Characterization of Alfalfa-Nodulating Rhizobia Present in Acidic Soils of Central Argentina and Uruguay
TLDR
Results demonstrate the complexity of the rhizobial populations present in the acidic soils represented by a main group of N2-fixing rhizobia and a second group of ineffective and less-predominant isolates related to the AT strain Or191. Expand
Cultural conditions required for the induction of an adaptive acid-tolerance response (ATR) in Sinorhizobium meliloti and the question as to whether or not the ATR helps rhizobia improve their symbiosis with alfalfa at low pH.
TLDR
It is shown here that an adaptive acid-tolerance response (ATR) can be induced in S. meliloti, and that the ATR represents a clear advantage in competing for nodulation at low pH. Expand
The transcriptional regulator gene phrR in Sinorhizobium meliloti WSM419 is regulated by low pH and other stresses.
TLDR
The phrR gene in Sinorhizobium meliloti WSM419, directly downstream from actA, is induced by low pH or certain stresses, but not in stationary phase or by other stresses (e.g. phosphate limitation, elevated temperature, high concentrations of sucrose or iron). Expand
The Sinorhizobium medicae WSM419 lpiA gene is transcriptionally activated by FsrR and required to enhance survival in lethal acid conditions.
TLDR
Although acid-activated lpiA transcription was not required for cell growth, its expression was crucial in enhancing the viability of cells subsequently exposed to lethal acid conditions and therefore this lipid cannot be a major constituent of S. medicae membranes. Expand
ActP controls copper homeostasis in Rhizobium leguminosarum bv. viciae and Sinorhizobium meliloti preventing low pH‐induced copper toxicity
TLDR
It is shown that copper homeostasis is an essential mechanism for the acid tolerance of these root nodule bacteria since it prevents this heavy metal from becoming overtly toxic in acidic conditions. Expand
Calcium affects the competitiveness of acid-sensitive and acid-tolerant strains of Bradyrhizobium japonicum in nodulating and fixing nitrogen with two soybean cultivars in acid soil
TLDR
This experiment indicates that addition of Ca per se as gypsum to an acid soil has little effect on symbiotic performance, but changing pH by liming has a major effect, that both soybean cultivar and B. japonicum strain influence the competitiveness of strains in acid soil and that acid-tolerance does not necessarily increase a strain's competitiveness. Expand
Probing for pH-Regulated Genes in Sinorhizobium medicae Using Transcriptional Analysis
TLDR
Findings implicate cytochrome synthesis, potassium ion cycling, lipid biosynthesis and transport processes as key components of pH response in S. medicae. Expand
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TLDR
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