AMINO ACID NUTRITION IN THE BLUE‐GREEN ALGA NOSTOC MUSCORUM

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Abstract
SUMMARY: The L‐isomers of 21 amino acids have been screened for their ability to serve as carbon or nitrogen sources for growth of the het+ nif−11 heterocystous and non‐nitrogen fixing mutant strain of the blue‐green alga Nostoc muscorum by a simple test system combining the use of 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) (an inhibitor of photosynthetic assimilation of CO2) and the auxotrophic (non‐nitrogen fixing) characteristic of the mutant. The amino acids glutamate, alanine, tyrosine and cysteine were toxic; glutamine, histidine, asparagine, tryptophan and serine were utilized as nitrogen sources; arginine, proline and phenylalanine were utilized as carbon sources; leucine, isoleucine, lysine, methionine, valine and citrulline were utilized as sources of both carbon and nitrogen; aspartate, threonine and glycine served neither as carbon nor nitrogen sources.