In Vitro Assessment of Antimicrobial Activity from Aqueous and Methanolic Extracts of Some Species of Cyanobacteria

Cyanobacteria have been identified as a new and rich source of bioactive compounds. Attention to the properties of cyanobacteria as a good source of secondary metabolites in the past was very low but today has been shown that these microorganisms have many applications in the medical field and pharmaceutical products. In this experimental study, the cyanobacteria of Synechococcus elangatus ISC 106, Fischerella ambigua ISC67 and Schizothrix vaginata ISC108‎ were obtained from the algal culture collection of research institute of applied science, ACECR, Tehran, Iran. Extraction was performed by adding the solvent to cyanibacteria biomass and then filtering and drying the mixture. Disk diffusion method was used to study the effect of antimicrobial and broth microdilution method was used to determine the minimum inhibitory concentration. The results showed that the methanol extract of Synechococcus elangatus had no significant effect on the bacteria, but the methanol extract of Fischerella ambigua showed antibacterial activity. Aqueous extract of Fischerella ambigua had significant effect on Gram-positive bacteria, so that maximum antibacterial activity was against Staphylococcus aureus (PTCC 1112) which the average zone diameter around it was 33.33 mm. Among tested extracts, only methanol extract of Fischerella ambigua ‎had inhibitory effects against four plant pathogenic fungi. The effect of aqueous extract Fischerella ambigua on Staphylococcus aureus (PTCC1112) and Staphylococcus epidermidis (PTCC1114) was more effective than all of the affecting antibiotics. The highest antibacterial activity of cyanobacteria was related to aqueous extract of Synechococcus elangatus and maximum effect of antifungal activity was related to methanol extract of Fischerella ambigua.Discussion and Among the three species of cyanobacteria, two species of cyanobacteria Fischerella ambigua, and Synechococcus elangatus had antimicrobial activity, thus it can be a good candidate for the extraction of antimicrobial compounds and many compounds found in these extracts can be used to monitor and inhibit many diseases.