Bioactivity in free-living and symbiotic cyanobacteria of the genus Nostoc

Fifty cyanobacterial strains of the genus Nostoc from soil, freshwater, marine waters, and symbioses were screened for bioactivity. Biomass from cultures was lyophilized and extracted with ethanol:water to obtain a hydrophilic extract, and then with dichloromethane:isopropanol to obtain a lipophilic extract. Tests of crude extracts for antifungal and antibacterial activity against specified organisms and for toxicity against Artemia salina nauplii revealed that 24 strains had activity against at least one target organism. Most bioactivity was directed at fungi and Artemia nauplii, and was equally divided between lipophilic and hydrophilic extracts. Strain origin did not influence bioactivity presence.