Abstract
A total of 8 bacterial strains associated with the surface of the oyster shells were isolated and four (COR1, COR2, COR5 and COR7) of them were found to have antagonistic activity. The intracellular and extracellular extracts of the antagonistic bacteria were isolated and subjected to antibacterial activity against biofilm-forming bacterium Alteromonas sp. Based on the results, the antagonistic bacterium Bacillus subtilis subsp. (COR5) which showed strong antibacterial activity was chosen for further antibiofilm and antifouling studies. Results of the antibiofilm assay showed significant (p?0.05) reduction in biofilm formation in the microtiter plate wells due to antagonistic bacterial intracellular and extracellular extracts treatment. Further, the antifouling coating prepared by incorporating bacterial extracts with epoxy resin revealed that the coating considerably resisted the recruitment of marine fouling organisms for the test duration of 50days in coastal waters. The bioactive fraction of the bacterial extracts was isolated using thin-layer chromatography (TLC) and the functional groups occurring in the active fractions of the intracellular and extracellular extracts were analyzed using Fourier transform infrared (FT-IR). In conclusion, the present study indicates that the bacteria associated with the shell surface of oysters could be used as a potential source for the exploration of novel antibacterial, antibiofilm and antifouling metabolites.