Effect of Cucurmin on Biofilm Formation by Fusobacterium nucleatum

Objectives: Fusobacterium nucleatum is a Gram-negative, anaerobic bacterium that plays an important role in dental plaque biofilm formation. The aim of this study was to evaluate the impact of cucurmin, a phytoalexin compound, on F. nucleatum biofilm formation.
Methods: The effects of cucurmin on biofilms formed on 96-well microtiter plates at 37°C were determined by MTT assay. Different concentrations of cucurmin (0.0, 5.0, 10.0 μg/ml) and different time points of biofilm formation (24 h, 36 h, 48 h) were investigated. The structures of the biofilm were observed by confocal laser scanning microscopy (CLSM), and gene expression (including FN0116, FN0503, FN0659, FN0675 and FN1856) was investigated by real-time PCR.
Results: The results showed that cucurmin at sub-MIC levels can decrease biofilm formation, whereas it does not affect the bacterial growth rate. It was observed by CLSM images that the biofilm became thinner and looser with increasing concentrations of cucurmin. Gene expression was down regulated in the biofilm in the presence of cucurmin.
Conclusions: Our results revealed that cucurmin can effectively inhibit biofilm formation by F. nucleatum.