Proteomic analysis of Fusobacterium nucleatum growth in biofilm versus planktonic state.

Fusobacterium nucleatum is isolated from both supra- and sub-gingival dental biofilms in humans and has been implicated in the aetiology of periodontitis. Also, this bacterium plays an important role in serious infections in other parts of the body. The aim of this investigation was to study the protein differential expression of F. nucleatum when growing on biofilm, compared to planktonic state, using proteomic analysis by the 2D-DIGE™ system. In all, 68 proteins were differentially expressed during biofilm growth (1.5-fold, p < .05), being 20 downexpressed and 31 overexpressed. The repressed proteins belonged to metabolism, biosynthesis and were outer membrane proteins (OMPs); and overexpressed were proteins involved in metabolism, transcription, translation, transport and proteins with unknown function. Also, of the seven enzymes that regulate the synthesis of butyrate, six of them were differentially expressed (overexpressed and downexpressed) when the bacteria were forming biofilms. The enzymatic activities of two of the enzymes in the butyrate pathway were analysed when the bacteria were growing in biofilms or in planktonic growth. All these results confirmed that this metabolic pathway is important in the formation of the biofilm of F. nucleatum and in its pathogenicity, both in the oral cavity and in other locations of the body.