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Response of a wild type and a non‐nitrogen‐fixing mutant of Anabaena doliolum towards different amino acids
Author(s) -
Kumar Ashok,
Kumar H. D.
Publication year - 1981
Publication title -
zeitschrift für allgemeine mikrobiologie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0044-2208
DOI - 10.1002/jobm.19810210502
Subject(s) - heterocyst , asparagine , glutamine , arginine , biochemistry , amino acid , biology , amino acid synthesis , anabaena , mutant , proline , alanine , leucine , wild type , glutamine synthetase , cyanobacteria , lysine , bacteria , genetics , gene
The effects of various amino acids on growth and heterocyst differentiation have been studied on wild type and a heterocystous, non‐nitrogen‐fixing ( het + nif − ) mutant of Anabaena doliolum. Glutamine, arginine and asparagine showed maximum stimulation of growth. Serine, proline and alanine elicited slight stimulation of growth of wild type but failed to show any stimulatory effect on mutant strain. Valine, glutamic acid, iso‐leucine and leucine at a concentration of as low as 0.1 mM were inhibitory to growth of parent type. Methionine, aspartic acid, threonine, cysteine, and tryptophan did not affect growth at concentrations lower than 0.5 mM. But at 1 mM, these amino acids were inhibitory. In addition to the stimulatory effects of glutamine, arginine and asparagine, the heterocyst frequency was also repressed by these amino acids. Glutamine and arginine at 2 mM completely repressed heterocyst differentiation in the mutant strain; however, other amino acids failed to repress the differentiation of heterocysts. Our results suggest that glutamine and arginine are utilized as nitrogen sources. This is strongly supported from the data of growth and heterocyst differentiation of mutant strain, where at least with glutamine there is good growth without heterocyst formation. Studies with glutamine and arginine on other N 2 ‐fixing blue‐green lagae may reveal the regulation of the heterocyst‐nitrogenase sub‐system.