In vitro evaluation of antimicrobial activities from aqueous and methanolic extracts of cyanobacteria

In this present study, antimicrobial activities of aqueous and methanolic extracts of cyanobacteria against some of fungi and pathogenic bacteria were investigated. Cyanobacteria strains Fischerella ambigua ISC67 and Schizothrix vaginata ISC108 were cultured in BG-11 medium. Extraction was performed by adding the solvent to cyanobacterial biomass and then filtering and drying of the mixture. The antimicrobial activity was evaluated by disc diffusion method and broth microdilution method was applied to determine the minimum inhibitory concentration. The results show that the aqueous and methanolic extracts of F. ambigua has a significant antimicrobial effect while, the tested extracts of S. vaginata was no significant antibacterial and antifungal activity. Highest antibacterial activity from aqueous extract of F. ambigua was against S. aureus (PTCC 1112) which the average zone diameter around it was 33.33 mm. The antibacterial effect of aqueous extracts against Gram-positive bacteria was more than Gram-negative bacteria significantly. Antifungal activity showed that methanolic extract of F. ambigua have significant antifungal activity. Minimum inhibitory concentration of active extract against most tested bacterial and fungal was 125 mg/ml. The present study has proved that the aqueous and methanolic extracts of F. ambigua possessed strong antibacterial and antifungal properties against the pathogenic microorganism. Therefore, cyanobacteria can be a rich source for natural products with antimicrobial activity. DOI: http://dx.doi.org/10.5281/zenodo.346363