Antimicrobial Potential of Maldivian Marine Macroalgae Against Clinically Relevant Bacterial Pathogens

The problem of antimicrobial resistance (AMR) is one of the major health problems globally predicted to claim lives of millions each year by 2050 unless new agents will be discovered. The marine environment such as Maldives archipelago with nearly 99% water coverage contains a variety of benthic macroalgae which still have not been explored to their full potential as a source of antimicrobials. This research deals with the assessment of antibacterial properties of two most common in Maldives benthic algae – Padina pavonica (brown algae) and Caulerpa racemosa (green algae). Fresh algae samples obtained from the intertidal areas of Hulhumale were shade-dried and extracted with 95% ethanol and distilled water under cold maceration technique to obtain crude extracts. After the experiment was performed and results were analyzed, it became clear that the ethanol extracts have shown greater extraction efficiencies and better antibacterial effects than aqueous extracts, which were not able to show any zones of inhibition. The strongest zone of inhibition was achieved with the ethanolic extract of P. pavonica on E. coli bacteria, while C. racemosa showed good suppression effect. While there was no visible inhibition effect against Klebsiella sp. and Enterococcus sp., the results have proved that the bioactivity of Maldivian algae depends on the solvent and strain and are very important to perform MIC/MBC assays.