611INHIBITION OF MARINE ALGAE EXTRACTS ON PORPHYROMONAS GINGIVALIS ORAL BIOFILM FORMATIONOral biofilm of Porphyromonas gingivalis as main etiological factor of chronic periodontitis may be addressed as target of periodontotherapy. Marine algae synthesize various secondary metabolites with potential inhibitory and reducing activities toward bacterial biofilm formation. In this research, red algae (Gracilaria sp. and Botryocladia sp.) and green algae (Enteromorpha sp., Halimeda opuntia, Caulerpa sertulaioides, C. racemosa, and Codium sp.) were investigated for their antibiofilm potentials through removing P. gingivalis biofilm in vitro. Algae were dried and extracted in ethanol, followed by evaporation and freeze-drying to produce algae crude powder. Algae extracts at various concentrations (5-250 µg/mL) were tested for their antibiofilm activity by performing in vitro P. gingivalis biofilm on the 96-well microtiter plate and quantifying the remaining biofilm cells using crystal violet assay. Three of 7 ethanolic algae extracts, i.e. Botryocladia sp., H. opuntia, and C. sertularioides, showed significant reducing activity against the existing P. gingivalis biofilm. The highest antibiofilm activity was reached by green algae extract of C. sertulariodes. At 5 µg/mL, C. sertulariodes reduced up to 50% P. gingivalis biofilm after 15 min exposure time. Our results suggest that selected marine algae may be potentially applied for periodontotherapy via reducing the existing oral bacterial biofilm in vitroyanti@atmajaya.ac.idResearch652015 Marine algae, Porphyromonas gingivalis,Oral biofilm,Antibiofilm activityYanti,Henry Tenurdin,Fendy Koesnoto, Jae-Kwan HwangFaculty of Biotechnology, Atma Jaya Catholic University, Jl Jenderal Sudirman 51, Jakarta 12930, Indonesia,Faculty of Biotechnology, Atma Jaya Catholic University, Jl Jenderal Sudirman 51, Jakarta 12930, Indonesia,Faculty of Biotechnology, Atma Jaya Catholic University, Jl Jenderal Sudirman 51, Jakarta 12930, Indonesia,Department of Biotechnology, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 120-749, Korea