Characterization of salt-tolerant and salt-sensitive mutants of Rhizobium leguminosarum biovar viciae strain C1204b.
Spontaneous mutants of Rhizobium leguminosarum biovar viciae strain C1204b were selected for their ability to tolerate 0.2 M NaCl, a growth-inhibiting level of salt for the parental strain. Transposon-mediated salt-sensitive mutants of strain C1204b were screened for their inability to grow in 0.08 M NaCl. Quantitation of the free-amino acid pools in the mutants grown in NaCl revealed a dramatic increase in glutamine, serine, glutamate and proline, and to a lesser extent alanine and glycine in the salt-tolerant mutants in comparison with the parental strain exposed to NaCl; but only glutamate and proline increased in the salt-sensitive mutants under NaCl stress. Extracellular polysaccharide levels were quantitated for the salt-tolerant mutants and determined to be approximately two-fold higher than for the parental strain. Although the mutations that occurred in the NaCl-tolerant and NaCl-sensitive strains did not interfere with nodule formation, no nitrogenase activity could be observed in the NaCl tolerant mutants as evaluated by acetylene reduction.
Chien
C T
CT
Department of Bacteriology and Biochemistry, University of Idaho, Moscow 83843.
Maundu
J
J
Cavaness
J
J
Dandurand
L M
LM
Orser
C S
CS
D000596:Amino Acids / Q000187:drug effects; D007887:Fabaceae / Q000382:microbiology; D009154:Mutation; D010641:Phenotype; D010946:Plants, Medicinal; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D016961:Rhizobium leguminosarum / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity
D000596:Amino Acids; D011135:Polysaccharides, Bacterial; D012965:Sodium Chloride