Photocatalytic bactericidal effect of TiO2 thin film on plant pathogens

Many plant pathogens such as Enterobacter spp., Pythium spp., and Fusarium spp. can be transmitted by irrigation water. The conventional bactericidal methods often apply chemical pesticides to the water. However, synthetic pesticides are hazardous to animals and the environment. Photochemical disinfection of plant pathogens with TiO2 thin film might offer an alternative method to disinfect plant pathogens from water. In this study, photocatalytic inactivation of Enterobacter cloacae SM1 and Erwinia carotovora subsp. carotovora ZL1 was evaluated on glass substrates coated with TiO2 thin film using the sol-gel process. The bactericidal activity was examined with 2, 3, 5-triphenyl tetrazolium chloride (TTC), an indicator of cell viability. The inhibition rates of TiO2 thin film against E. cloacae SM1 and E. carotovora subsp. carotovora ZL1 bacteria treated with ultraviolet A (UV-A) light irradiation for 60 min were 99.5% and 99.9%, respectively. The disinfection efficiency with TiO2 thin film is relatively constant at pH values in the range of 5.8 to 8.0. The results suggested that photocatalytic phytopathogen inactivation with TiO2 thin film has the potential for use as a new tool for plant protection in recycled water systems. (c) 2006 Elsevier B.V. All rights reserved.