Screening of Seaweeds for Antibacterial and Antifungal Activities

Commonly occurring seaweeds, Caulerpa scapelliforms, Ulva lactuca, Padina tetrastromatica, Steochspermum marginatum and Acanthophora spicifera collected from the Tuticorin coast, Tamil Nadu (India) were evaluated for antibacterial and antifungal activity by agar diffusion method. Four different solvents viz. petroleum ether, benzene, chloroform, and methanol wereused for extraction. By using commercial medicine, Amikacin-AK30-30mcg/disc, Cephalexin-CN30-30mcg/disc, Ciprofloxacin-CIP5-5mcg/disc and Fluconazole-FLC25-25mcg/disc as control and zones of inhibition were compared. The seaweed extracted using petroleum ether as a solvent showed the best antifungal activity and was more effective than commercial antibiotic, fluconazole. None of the extracts were active against Staphylococcus aureus, a gram-positive bacterial pathogen. The methanol extract was active against Salmonella typhi, Pseudomonas aeruginosa, Proteus vulgaris, and Escherichia coli except for Caulerpa scapelliforms and Ulva lactuca. All the four extracts of Acanthophora spicifera showed antibacterial activity.