AWWA ACE70780

This powerpoint presentation begins by providing a brief overview of ultraviolet- (UV)- C disinfection. Research objectives include: compare the DNA damage and repair of E. coli after UV-C and UV/TiO₂ disinfection; and, explore the possible mechanism of the reactivation repression effect by UV/TiO₂ disinfection. Methodology included: microorganism - Strain: E. coli K12 JM109; UV-C and UV/TiO₂ irradiation; and, Endonuclease Sensitive Site Assay (ESS Assay). Presentation summary indicates that: E. coli DNA dimer repair is obstructed by UV/TiO₂ irradiation, probably resulting in subsequent photoreactivation repression; the direct damage to the photoreactivating enzyme may not be the main reason to the repression of dimer repair, it requires further investigation; and, the photoreactivation can be partially attributed to the increase of oxidative stress in bacteria by UV/TiO₂ and UV/H₂O₂ irradiation. Includes tables, figures.