Identification and localization of proteins associated with the formation of Streptococcus gordonii and Fusobacterium nucleatum biofilms
Abstract Background:To successfully colonize the oral cavity, bacteria must adhere directly or indirectly to the oral surfaces available. Fusobacterium nucleatum plays an important role in the development of the oral biofilm community due to its broad adhesion capabilities, serving as a bridge between the members of the oral biofilm community that cannot be directly joined together. The purpose of this study was to identify and localize the proteins associated with the formation of biofilms of Streptococcus gordonii and F. nucleatum. Methods: Multispecies biofilms were identified by amplification of the srtA and radD genes by real-time PCR. Biofilm cells cultured with sucrose were counted. The protein concentrations in the membrane and cytoplasmic fractions were quantified by western blot. Results: The proteins HSP40 and GAPDH were detected in the cytoplasmic fraction of biofilm and F. nucleatum, respectively. The available anti-GAPDH antibody is specific for GAPDH produced by F. nucleatum, which indicated the coaggregation of F. nucleatum on S. gordonii. Conclusions: HSP40 was only detected in the cytoplasmic fraction of the biofilms, making it one of the essential proteins for adherence. This complex set of interactions could have critical implications for the formation and maturation of oral biofilms in vivo and could provide clues to the mechanism behind the distribution of organisms within the human oral cavity.