Open AccessCharacterization of salt‐tolerant and salt‐sensitive mutants of Rhizobium leguminosarum biovar viciae strain C1204b *
Author(s) -
Chien ChingTe,
Maundu Josephine,
Cavaness Jeff,
Dandurand LouiseMarie,
Orser Cindy S.
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05140.x
Subject(s) - rhizobium leguminosarum , mutant , strain (injury) , biology , proline , biochemistry , glycine , rhizobium , microbiology and biotechnology , chemistry , rhizobiaceae , amino acid , bacteria , symbiosis , genetics , gene , anatomy
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.