Photocatalytic disinfection of E. coli using tourmaline-N-doped TiO2 composite

J-H Tzeng, Y-T Lin, C-H Weng
National Chung Hsing University, TW

Keywords: AFM, E coli, inactivation, photocatalytic

Summary:

Neither the microbicidal mechanism of TiO2 under visible radiations nor their potential effects in the light intensity have yet been well established. In this paper, the photocatalytic inactivation of bacteria was investigated using E. coli, because it is a well-known bacterial model. First of all, we focused on the effects of the contact of tourmaline-N-doped TiO2 with bacterial cells in the dark on both the bacterial cultivability and the envelope integrity. Then, under visible radiations exposure, we assessed the deleterious effects of tourmaline-N-doped TiO2 on the bacteria’s permeability and cultivability. We also monitored ions and carboxylic acids in order to identify chemical by-products released during the inactivation of the bacteria. Furthermore, using TEM and AFM analysis, we correlated damages to E. coli structures with their loss of cultivability. Finally, we studied the damages of chromosomic DNA and RNA at in vivo level with the photocatalytic damages of the microorganisms.