Evaluation of photocatalytic processes in aqueous environments and on dry surfaces using titanium dioxide for bacterial inactivation

In the present study, TiO2 photocatalysis has been investigated for the inactivation of pathogenic bacteria Escherichia coli ATCC 11303, Staphylococcus aureus SH1000 wild type, SH1000 ahpC/katA catalase mutant strains and SH1000 sodA/sodM superoxide dismutase mutant strains. The same dose of UVA light given at different light intensities resulted in different intracellular oxidative stress and bacteria inactivation kinetics especially for bacteria in presence of TiO2 coatings. The inactivation results obtained did not follow the Bunsen–Roscoe reciprocity law which is applicable for simple photochemical processes. Differences were observed in the intracellular response and subsequent killing of S. aureus upon exposure to UVA and these were found to be dependent on the level of intensity of irradiation and not the total UVA dose. [Continues.]