ANTIMICROBIAL PROPERTIES OF EDIBLE SEAWEEDS, RHODOMENIA PALMATA AND SARGASSUM SWARTZII FROM THE GULF OF MANNAR SOUTH COAST, MANAPPAD, SOUTH INDIA

Nowadays, intensive use of several forms of synthetic antibiotics to treat bacterial infections has resulted dramatically in emergence of resistant pathogenic microorganisms, often due to indiscriminate use of these substances. The present study was carried to evaluate the antibacterial and antifungal activities of different concentrations of methanol extracts of Rhodomenia palmata and Sargassum swartzii collected from Manappad, the Gulf of Mannar Biosphere Reserve, Tamil Nadu, India. The methanol extracts of selected two marine macro algae were screened against Bacillus subtilis, B. pumilus, Micrococcus luteus, Staphyloccous aureus, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Streptococcus pyogenes, Proteus mirabilis, Proteus vulgaris, Shigella flexneri, Salmonella enterica, Vibrio chloerae and five yeast viz., Candida albicans, C. glabarata, C. tropicalis, C. krusei, C. parapsilosis, C. guilliermondii, Merozyma gulliermondii and Candida lusitaniae and nine mould fungi namely Aspergillus niger, A. flavus, A. fumigatus and A. clavatus four dermatophytes viz., Trichophyton rubrum and T. mentagrophytes strains. The antimicrobial activity was determined the extent of inhibitory zones using disc diffusion method, Minimum inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). The mean zones of inhibition ranged from 7.1 to 21.5 mm. The MIC values of the methanol extracts of the tested organisms ranged between 62. 5 and 250 µg/ml, while the MBC and MFC values were between 250 and 500 µg/ml. The highest antibacterial activity was recorded in the ethyl acetate extract of R. palmata than other extracts. The overall results have established antimicrobial activities of R. palmata and S. swartzii could be used against several diseases and, in the food processing industry, to preserve foods.