Isolation and characterization of nonheterocystous tropical cyanobacteria growing on nitrogen-free medium

Fourteen non-heterocystous cyanobacteria were selected from a continuous waterlogged biotope on a mineral medium free of combined nitrogen. Following morphological characterization, four, nine and one of the strains respectively, were assigned to sections I, II and III of a new cyanobacterial classification. Their phenotypic properties, including growth rates, photoheterotrophy, phycobiliprotein content, antibiotic resistance and toxin production were determined. Three strains were found to harbour one to three plasmids of low molecular weight.