Cyanobacterial fatty acid esters disrupt polymicrobial oral biofilms and exhibit potential interactions with adhesion proteins and virulence-associated targets.

OBJECTIVE: Oral biofilm-associated infections are difficult to manage because of their polymicrobial nature, antimicrobial tolerance, and involvement in chronic oral diseases. This study evaluated the antimicrobial, anti-biofilm, and antioxidant potential of bioactive metabolites from the freshwater cyanobacterium Oscillatoria sp. PB602 against oral biofilm-associated pathogens and clinically relevant opportunistic colonizers implicated in complex oral infections.

DESIGN: Methanolic extracts of Oscillatoria sp. PB602 were evaluated against oral pathogens and opportunistic colonizers, including Streptococcus mutans, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans, using agar diffusion and Minimum Inhibitory Concentration (MIC) assay. Anti-biofilm activity was assessed by crystal violet staining and Confocal Laser Scanning Microscopy (CLSM), while bioactive metabolites were characterized using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FT-IR). Molecular docking analysis was performed to investigate potential interactions with biofilm-associated virulence proteins.

RESULTS: The extract demonstrated concentration-dependent antimicrobial activity, with the highest inhibition observed against C. albicans (16 mm at 100 μg/mL). MIC analysis showed > 88% inhibition of mixed-species biofilms. Crystal violet assays revealed an 84% reduction in biofilm biomass, while CLSM confirmed ∼87% microbial cell death in mature biofilms at 2.5 × MIC. GC-MS identified fatty acid esters, including oleic acid derivatives, and FT-IR confirmed hydroxyl, carbonyl, and amine functional groups. Docking analysis indicated moderate binding affinity toward virulence-related proteins, with binding energies up to -5.8 kcal/mol.

CONCLUSION: Oscillatoria sp. PB602 exhibited antimicrobial, anti-biofilm, and antioxidant activities against oral biofilm-associated pathogens and opportunistic colonizers, supporting its potential as a natural source of bioactive metabolites for oral healthcare applications and contributing to Sustainable Development Goal (SDG) 3 (Good Health and Well-being) through the advancement of preventive oral healthcare strategies.