Antifouling potentials of extracts from seaweeds, seagrasses and mangroves against primary biofilm forming bacteria

To screen the antifouling potential of various extracts from seaweeds (Ulva reticulate, Sargassum wightii, Halimeda macroloba), sea grasseses (Halodule pinifolia, Cymodocea serullata) and mangrove plants (Rhizophora apiculata, Rhizophora mucronata and Avicennia marina) against some marine fouling bacteria. The different species of seaweeds, seagrasses and mangrove samples were collected, washed, air dried and fine powdered samples were subjected to solvent extraction by cold steep method. The extracts fraction was eluted with the ethanol and subjected to FTIR. The biofilm forming bacteria were scrapped from the marine environment by biofilm formed PVC sheet. Among these ten strains isolated, four isolates (Flavobacterium sp., Bacillus sp., Cytophaga sp., Pseudomonas sp.) were chosen for this study. Among the tested extracts, Avicennia marina limited the growth of Flavobacterium sp. (16 mm) and Bacillus sp. (20 mm) and the extracts of Rhizophora mucronata limited the growth of Flavobacterium sp. (18 mm) and Bacillus sp. (18 mm). While comparing the inhibition activity of all the extracts, mangrove plants extracts had higher inhibiting activity against primary biofilm forming bacteria than seaweeds and seagrasses. The inhibition activity was mainly correlated with the major functional groups [hydroxyl, amino, carbonyl and phosphoryl functionalities, aliphatic (fatty acids), NH2 (amide I & II)] of the extracts. The bioactive fractions from the above results indicates the occurrence of active constituents in the extracts of seaweeds, seagrasses and mangrove. It shows the improved antifouling activity against marine micro-fouling bacteria. These extracts can be used as the possible natural sources for anti-foulant.