Listeria monocytogenes Behaviour in Presence of Non-UV-Irradiated Titanium Dioxide Nanoparticles

Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO(2) NPs) are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO(2) NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS) with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO(2) NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO(2) NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO(2) NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO(2) NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts.