Response of a wild-type and a non-nitrogen-fixing mutant of Nostoc linckia to different carbon sources

Abstract

The wild-type parental strain and a het⁺nif^- mutant of Nostoc linckia grow heterotrophically in light, with and without DCMU, and in darkness when supplemented with a source of carbon. Glucose and sucrose stimulated heterocyst production. Glucose enhanced the uptake of ammoniacal nitrogen from the medium when parent and mutant were grown in an ammonium-supplemented medium. Effects of cAMP (sodium salt and dibutyryl), with and without glucose, on growth and heterocyst differentiation of parent and mutant were studied. Dibutyryl cAMP, in general, was found to be toxic to the alga, but the sodium salt of cAMP enhanced growth with glucose. The mutant grew well in a nitrogen-free medium supplemented with cAMP.