Hello Dear, these articles may help you:

Article Phenotypic and Genotypic Comparison of Symbiotic and Free-Li...

Article Isolation of axenic cyanobacterium and the promoting effect ...

Article Morphological and genetic diversity of symbiotic cyanobacter...

Article Isolation of cyanobacteria from the aquatic fern, Azolla

Article Growth of the Cyanobacterium Synechococcus leopoliensis CCAP...

It could be many different bacteria. It all has survive together in nature; but isolated, there will be competition. Perhaps re-isolate your cyanobacteria to try too get rid of it. That is easier than trying to identify it.

Cyanobacterial symbioses are no longer regarded as mere oddities but as important components of the biosphere, occurring both in terrestrial and aquatic habitats worldwide. It is becoming apparent that they can enter into symbiosis with a wider variety of organisms than hitherto known, and there are many more still to be discovered, particularly in marine environments. The chapters cover cyanobacterial symbioses with plants (algae, bryophytes, Azolla, cycads, Gunnera), cyanobacterial symbioses in marine environments, lichens, Nostoc-Geosiphon (a fungus closely related to arbuscular mycorrhiza fungi) symbiosis, and artificial associations of cyanobacteria with economically important plants. In addition, cyanobiont diversity, sensing-signalling, and evolutionary aspects of the symbiosis are dealt with. Renowned experts actively involved in research on cyanobacterial symbioses deal with ecological, physiological, biochemical, molecular, and applied aspects of all known cyanobacterial symbioses. This volume on cyanobacteria in symbiosis complements the two earlier volumes on cyanobacteria published by Kluwer (Molecular Biology of Cyanobacteria, edited by D.A. Bryant and Ecology of Cyanobacteria, edited by B.A. Whitton and M. Potts). Together, the three volumes provide the most comprehensive treatment of cyanobacterial literature as a whole. The book will serve as a valuable reference work and text for teaching and research in the field of plant-microbe interactions and nitrogen fixation.