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Biochemical characterization of a shikimic acid‐resistant mutant of Nostoc linckia
Author(s) -
Kumar Dhruv
Publication year - 1989
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620290609
Subject(s) - mutant , shikimic acid , nitrogenase , biochemistry , wild type , biology , ammonium , glutamine , population , microbiology and biotechnology , bacteria , chemistry , amino acid , nitrogen fixation , genetics , demography , organic chemistry , sociology , gene
The growth of Nostoc linckia was significantly inhibited by shikimic acid concentrations greater than 4.0 μg ml −1 and was completely inhibited at 10.0μg ml −1 . Shikimic acid increased the duration of the lag phase and the doubling time and hastened the onset of the retardation phase of growth. A mutant ( NL shi ) capable of growing in presence of 50 μg ml −1 shikimic acid, was isolated by nitrosoguanidine mutagenesis from the wild type population at a frequency of about 1 × 10 −5 to 1 × 10 −6 . The mutant grew slower than the wild type. Both the wild type and the mutant strain grew photoheterotrophically in light, with and without 3 (3–4 dichlorophenyl) 1,1‐dimethyl urea (DCMU) and in darkness when provided with glucose. Glucose supplementation promoted ammonium uptake from the medium, when wild type and mutant were grown in an ammonium‐supplemented medium. Glucose stimulated heterocyst production and nitrogenase activity in both the strains. As compared to wild type, this mutant showed higher heterocyst frequency and nitrate reductase activity but its ammonium uptake activity was lower. No significant difference in glutamine synthetase and nitrogenase activities of the mutant were observed. The mutant was stable and retained its resistance even after several subcultures through medium free of shikimic acid.