Antibiotic production by the cyanobacteria Oscillatoria angustissima and Calothrix parietina.

The accumulation of antibiotic in the medium is temperature dependent and not in direct proportion to growth parameters. The cyanobacterial product suppressed growth of some natural isolates of cyanobacteria and green algae. It inhibits the growth rate and oxygen evolution of the green alga, Chlorella fusca. The antibiotic also inhibits the growth of bacteria and some fungi, especially the dermatophytes. Generally eukaryotic organisms were less sensitive than prokaryotic. Experimental mice were unaffected by the antibiotic. The Oscillatoria antibiotic does not structurally resemble to cyanobacterin.