RESUMEN
In vitro screening of organic solvent [diethyl ether, ethyl acetate and ethanol] extracts of Rivularia species and Oscillatoria salina were carried out against some pathogenic bacteria E. coli, S. aureus, P. aeruginosa, E. faecalis, Acinetobacter species and P. mirabilis. Two marine cyanobacteria Oscillatoria salina and Rivularia species were collected from Mediterranean Sea shore, Misurata, Libya. Both cyanobacterial strains were extracted with diethyl ether, ethyl acetate and ethanol. In vitro screening of antibacterial activity of the crude extracts were carried out against six common pathogenic bacteria E. coli, S. aureus, P. aeruginosa, E. faecalis, Acinetobacter species and P. mirabilis. The extracts were tested in compliance with the agar well diffusion and disc diffusion method for their antibacterial activity. Diethyl ether extract of Rivularia species showed moderate inhibitory activity against P. mirabilis [5mm] and Acinetobacter species [5mm] and ethylacetate extract of that species showed little activity against Acinetobacter species [3mm] P. mirabilis [2mm]. Ethanol extract of Rivularia species showed no activity to that selected bacteria. Diethylether extract of Oscillatoria salina showed little activity only against Acinetobacter species [2mm] and the remaining two solvent extracts had shown no activity against that above mentioned pathogenic bacteria. Diethyl ether crude extract of Rivularia species possessed noticeable antibacterial activity against gram negative bacteria when compared with standard Ampicillin and Streptomycin. It is evident from the present study that the diethyl ether and ethyl acetate extract of Rivularia species could be utilized as an antibacterial agent in pharmaceutical industry