Regulation of exopolysaccharide production in Rhizobium leguminosarum biovar viciae WSM710 involves exoR

Article Abstract:

A number of Tn5-induced acid sensitive mutants of Rhizoium meliloti and rhizobium leguminosarum bv. viciae were isolated to determine the basis of acid tolerance in Rhizobium. Results indicat the discovery of a mutant of R. leguminosarum bv. visiae WSM710 (WR6-35) which showed a more mucoid phenotype on minimal medium than the parent. Furthermore, it was found that Tn5 disrupted a gene encoding regulatory protein (ExoR) which negatively modulates the biosynthesis of EPS in R. leguminosarum bv. viciae WSM710.

Mutagenesis, Soil acidity

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An essential role for actA in acid tolerance of Rhizobium meliloti

Article Abstract:

The DNA sequence of the actA gene, predicted nature of the ActA protein, its similarity to the cutE gene of Escherichia coli, its distribution in a range of bacteria and its expression at acidic and neutral pH are presented. The rhizobial gene is required to isolate and sequence an acid-tolerant phenotype. The membrane-pound, lipid-metabolizing protein can be compared to the Cut/Lnt protein of enteric bacteria, which, when inactivated, becomes prone to environmental stress.

Heredity

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Acid tolerance in Rhizobium meliloti strain WSM419 involves a two-component sensor-regulator system

Article Abstract:

The TG5-46 mutant, arising from Tn5 mutagenesis of Rhizobium meliloti, shows acid sensitivity due to inactivation of actR or actS genes in R. meliloti WSM419. DNA sequence analysis reveals ORF1 (actR) and ORF2 (actS), open reading frames flanking Tn5 in TG5-46, as sensor-regulator system controlling expression of genes involved in resistance to pH lower than 6.0. Acid sensitivity is directly related to the presence of Tn5 in TG5-46.

Analysis, Genetic aspects, Microbial mutation, Hydrogen-ion concentration, Rhizobium meliloti

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