Screening of medicinal plant extracts for eco-friendly antimicrofouling compounds G. IMMANUEL*, P. IYAPPARAJ, R. RAMASUBBURAYAN, A. PALAVESAM and PETER M. MARIAN Centre for Marine Science and Technology, M.S. University, Rajakkamangalam, Kanyakumari District, Tamil Nadu, India Abstract The diversified biofouling organisms cause damage to fishing vessels including accessory materials in marine environment. Their occurrence and diversity are influenced by environmental variables. In the harbor environment, their growth is favored by pollutants from anthropogenic activities, a fact deserving critical investigation. The site selected for the present study is Chinnamuttom fisheries harbor in southeast coast of India. Four different substrata (panels), i.e. wood, FRP, stainless steel and carbon steel were selected and exposed to seawater of fisheries harbor for 72 h. From these panels, the biofilm was scrapped out at an interval of 24 h for a period of 72 h and then the total viable count (TVC) of the biofilm was enumerated. It showed a gradual increase of TVC with increase in time. Among the tested substrata, stainless steel showed the highest (30.0-85.30 x 104 CFU ml-1) bacterial load against the lowest (10.3-19.6 x 104 CFU ml-1) in carbon steel. In total, eight bacterial species were isolated and identified from all panels, with varying population diversity. The daily variations in physico-chemical parameters of the source water showed little fluctuation. Further, the methanolic extracts of 10 selected medicinal plants were screened for antimicrofouling properties against the identified bacterial species. Among the medicinal plants screened, Phyllanthus niruri exhibited the highest inhibitory activity against all tested bacterial species (12.0-14.0 mm). Lawsonia innermis (10.0-12.5 mm), Azadirachta indica (9.5-11.5 mm), and Aloe vera (8.5-10.5 mm) exhibited considerable antimicrofouling property. Plant extracts with their active principle compounds were evidenced to be essential components for the preparation of biofilm repellents.   < back .