Effect of TiO2 on Selected Pathogenic and Opportunistic Intestinal Bacteria

Food-grade titanium dioxide (TiO 2 ) containing a nanoparticle fraction (TiO 2 NPs-nanoparticles) is widely used as a food additive (E171 in the EU). In recent years, questions concerning its effect on the gastrointestinal microbiota have been raised. In the present study, we examined interactions between bacteria and TiO 2 . The study involved six pathogenic/opportunistic bacterial strains and four different-sized TiO 2 types: three types of food-grade E171 compounds and TiO 2 NPs (21 nm). Each bacterial strain was exposed to four concentrations of TiO 2 (60, 150, 300, and 600 mg/L TiO 2 ). The differences in the growth of the analyzed strains, caused by the type and concentration of TiO 2 , were observed. The growth of a majority of the strains was shown to be inhibited after exposure to 300 and 600 mg/L of the food-grade E171 and TiO 2 NPs.