Antimicrobial activity of Cyanobacteria isolated from hot spring of Geno

Cyanobacteria, the blue green algae are one of the most diverse groups of Gram-negative photosynthetic prokaryotes widely distributed throughout the world. Cyanobacteria are known to produce a wide range of secondary metabolites with various biological actions. The aim of this study was to test extracts from various cyanobacteria isolated from Geno hot spring, Bandar Abbas (Iran) against a diverse range of organisms comprising Gram-positive and Gram-negative bacteria and yeasts to evaluate its antibacterial and antifungal activities. Seven species namely Oscillatoria subbrevis, O. tenuis, O. limentica, O. angusta, O. articulate, Synechocystis aquatilis and Synechoccous cerdorum were selected for the production of antimicrobial agents against five Gram-positive and three Gram-negative bacteria, and two fungi. The results of this study showed that the methanol extracts exhibited high antimicrobial activity against some Gram positive bacteria (Bacillus subtilis and B. pumulis), moderate antibacterial activity against the some Gram negative organisms (Escherichia coli) and moderate antifungal activity against some fungi (S. cerevisiae).