Online) An Open Access

ABSTRACT Cyanobacteria are rich source of primary and secondary metabolites which are important in biotechnology and pharmaceutical industries. The aim of the present study was to collect and identify 2 cyanobacteria (Lyngbya sp, Osilatoria sp) from Shahid Rajaee Hydrothermal freshwater fish pool in the city of Sari, Iran. Agar diffusion method was used to test antibacterial and antifungal activity on human pathogenic bacteria and fungi (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Streptococcus mutants, Escherichia coli, Klebsiella pnuemoniae, Saccharomyces cerevisiae and Candida albicans). The antimicrobial activity of the named cyanobacteria was compared using different solvents (ethanol, acetone, diethyl ether and methanol). It was shown that ethanol and methanol extracts of Osillatoria have the highest antibacterial activity. Additionally, it was found that Oscillatoria sp and Lyngbya sp have antifungal activity against Candida albicans. Diethyl ether extracts of Oscillatorya sp and Lyngbya sp had the highest antifungal activity. Additionally, diethyl ether extract of the cyanobacterium Lyngbya sp had the highest antibacterial activity against E. Coli