In vitro Antibacterial Activity of Methanol, Ether and Aqueous Extracts in Some Species of Cyanobacteria

Background and Cyanobacteria are rich sources of secondary metabolites. Antibiotic resistant pathogens are rising and people are more interested in using natural products these days. Hence, identifying competent cyanobacteria for the extraction of antimicrobial compounds is of great benefit. The main objective of this study was to investigate the in vitro antibacterial activity of methanol, ether and aqueous extracts of some species of cyanobacteria. In this experimental study, the cyanobacteria of Fischerella ambigua, Synechococcus elongatus and Schizothrix vaginata were obtained from the culture collection of algae at the Iranian Academic Centre for Education, Culture and Science. Extraction was performed by adding the solvent to cyanobacterial biomass and then filtering and drying of the mixture. The antimicrobial effect was studied using disk diffusion method and broth microdilution method was applied to determine the minimum inhibitory concentration. Results showed that methanol, ether and aqueous extracts of Fischerella ambigua and aqueous extract of Synechococcus elongatus had considerable antibacterial activity. Ether extract of Fischerella ambigua was the most effective against Staphylococcus aureus and Staphylococcus epidermidis, and the average diameter of inhibition zone were 31/67 and 32/67 mm, respectively. The most effective extracts against gram-negative and gram-positive bacteria were the aqueous extract of Synechococcus elongatus and the ether extract of Fischerella ambigua, respectively. Two species of cyanobacteria Fischerella ambigua and Synechococcus elongatus were found with significant antimicrobial activity. The aqueous extract of Synechococcus elongatus was the best for isolation of antibacterial compounds and diethyl ether was an efficient solvent for the extraction of antimicrobial compounds from Fischerella ambigua species.