Antibacterial Activity of Some Selected Algae Present in the Costal Lines of Jaffna Peninsula

In this study, Sargassum polycystum, Sargassum tenerrimum, Turbinaria ornata, Gracilaria crassa and Codium fragile were tested for their phytochemical constituents and antibacterial activity. The algae were collected from different coastal sites in Jaffna peninsula. The fine algal powders were directly extracted with ethanol and sequentially extracted with acetone and ethanol. The resulting extracts were subjected with qualitative phytochemical analysis and for their antibacterial activity against Escherichia coli (ATCC 25922) and Staphylococcus aureus (NCTC 6571) by agar well diffusion method. The one way analysis of variance (ANOVA) followed by Tukey test was used for statistical analysis. Phytochemical analysis of extracts revealed the presence of at least two of the phytochemicals among the tested alkaloids, saponins, flavonoids, tannins and cardiac glycosides. The antibacterial study demonstrated that except acetone extract of S. tenerrimum, all other tested extracts were able to inhibit the growth of both S. aureus and E. coli. The sequential extracted ethanol extracts and direct ethanol extracts exhibited significantly (P < 0.05) higher inhibition on S. aureus compared to acetone extracts of respective algae. On the other hand, acetone extracts showed better activity on E. coli compared to the effect expressed on S. aureus. However, the highest inhibitory effect on E. coli and S. aureus was produced by the sequentially extracted ethanol extract of C. fragile and T. ornata respectively. The present study concluded that macro algae collected from different coastal lines of Jaffna peninsula are potential sources of bioactive compounds and can be used as source for antibacterial agent.