Surface characterization of Streptococcus mutans biofilms grown on polyethylene and beta-titanium

Abstract

In this study, we considered the biofilms as a surface, characterizing them using instruments for surface analyses, environmental microscopy, IR-spectroscopy (ATR-mode) and goniometry of the contact angle. The bacteria that formed the biofilms were grown on two different supports: beta-titanium alloy (beta-Ti) and polyethylene (PE). Environmental microscopy allowed the observation of biofilms in situ and in their hydrated state. On the metallic support, the biofilm quickly adhered and formed a dense structure with micro-colonies, but on the PE a thinner biofilm layer was observed covering a large surface area of the support. IR-spectroscopy is another effective method to detect the biofilm quickly and in situ, without pre-treating the sur-face. Nevertheless, problems with the overlapping of the characteristic bands on the spectra are frequent between the biofilm and PE. Finally, we compared the surface energy (SE) of the supports before and after biofilm formation. Our results indicate that the SE of the supports depends on the sterilization method, and that the SE of the biofilms varies depending on the support and the sterilization method. The biofilm on the beta-Ti had the highest SE, and as mentioned above, microscopic images showed a higher roughness on its surface.