Rhizobium tropici response to acidity involves activation of glutathione synthesis

Muglia, Cecilia Isabel; Grasso, Daniel H.; Aguilar, O. Mario

doi:10.1099/mic.0.2006/003483-0

Cited by 31 publications

(20 citation statements)

References 58 publications

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“…A study by Küçük and Kivanç indicates that extreme values of pH result in dramatic decreases in EPS yields, particularly in the acidic range (Küçük and Kivanç 2009). Similar results have been observed by others; while the pH optimum for exopolysaccharide production depends on the individual bacterial species, for most species, it tends to be near neutrality (Williams and Wimpenny 1977;Vermani et al 1997) and constant (Morin 1998). We have found this to be the case with R. tropici where our two acidic trials formed less EPS than the trials cultured closer to neutral pH.…”

Section: Discussionsupporting

confidence: 69%

Variations in exopolysaccharide production by Rhizobium tropici

2011

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Rhizobium tropici, a legume-symbiont soil bacterium, is known for its copious production of exopolysaccharide (EPS). Many aspects of this organism's growth and EPS production, however, remain uncharacterized, including the influence of environment and culturing conditions upon EPS. Here, we demonstrate that R. tropici EPS chemical composition and yield differ when grown with different substrates in a defined minimal medium in batch culture. Exopolysaccharide was quantified from R. tropici grown using arabinose, glucose, sucrose, mannitol, fructose, or glutamate as a sole carbon source. All tested substrates produced plenteous amounts of exopolysaccharide material. Variations in pH and carbon-to-nitrogen (C/N) ratio also resulted in assorted cell growth and exopolysaccharide production differences. We found that optimizing the C/N ratio has a greater impact upon R. tropici EPS production than upon R. tropici growth. A maximum EPS yield of 4.08 g/L was realized under optimized conditions, which is large even in comparison with other known rhizobia. We provide evidence that the chemical composition of R. tropici EPS can vary with changes to the growth environment. The composition of glucose-grown EPS contained rhamnose-linked residues that were not present in arabinose-grown EPS.

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Section: Discussionsupporting

confidence: 69%

Variations in exopolysaccharide production by Rhizobium tropici

2011

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“…The CIAT 899 and PRF 81 genomes encoded a homologue of kcsA , a Streptomyces lividans ion channel that opens at low pH allowing K + entrance into the cell. Riccillo et al [24] found that the glutathione synthase gshB gene is required for CIAT 899 tolerance to acidic stress, its activation occurring under low-pH conditions [174]. The inability of a CIAT 899 gshB mutant to grow in low-pH media was related to a diminished capacity to accumulate K + at low pH, and it was proposed that a KefB/KefC glutathione-regulated K + efflux transporter may be too active in the absence of glutathione [24].…”

Section: Resultsmentioning

confidence: 99%

Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.)

et al. 2012

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BackgroundRhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown.ResultsGenome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym) that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins.ConclusionsAvailability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.

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“…A series of authors demonstrated that the efficacy of nodule formation of R. tropici is increased under acidic conditions, whereas R. leguminosarum, on the contrary, exhibited decreased nodule formation under the same conditions (Martínez Romero et al, 1991;Muglia et al, 2007). We revealed high homology of some symbiotic genes of these bacteria with analogical It is possible that Agrobacterium sp.…”

Section: Resultsmentioning

confidence: 63%

Genetic description of root nodule bacteria of Lathyrus species growing on the territory of the Republic of Bashkortostan

Baymiev

Ptitsyn

Мулдашев

et al. 2012

Russ J Genet Appl Res

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The genetic diversity and phylogeny of rhizobia isolated from nodules of nine wild growing Lathyrus L. species (Fabaceae) growing in the Republic of Bashkortostan were studied. It is shown that, for the given plants, a large variety of heterogeneous strains of root nodule bacteria is characteristic. Nevertheless, it is revealed that the majority of them, in terms of phylogenetics, are closely related to Rhizobium leguminosa rum. However, some plant species are found also: nodule bacteria, which were earlier considered unusual for Lathyrus. Thus, L. vernus L. Bernh. and L. sylvestris L. are found to have a root nodule bacteria close to R. tropici, L. palustris L. Agrobacterium sp., and L. gmelinii Fritsch, all bacteria isolated by us from root nodules by the sequence of genes of 16S rRNA, are closely related to Phyllobacterium myrsinacearum.

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Rhizobium tropici response to acidity involves activation of glutathione synthesis

Cited by 31 publications

References 58 publications

Variations in exopolysaccharide production by Rhizobium tropici

Variations in exopolysaccharide production by Rhizobium tropici

Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.)

Genetic description of root nodule bacteria of Lathyrus species growing on the territory of the Republic of Bashkortostan

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