Inactivation of phage Q beta by 254nm UV light and titanium dioxide photocatalyst

Abstract

The disinfection efficacy of UV light irradiation at wavelength of 254 nm over a titanium dioxide (TiO2) suspension was compared to that of UV alone. Bacteriophage Q beta was used as a model virus for the study. Q beta in sterilized pure water and TiO2 suspension was irradiated by a 0.4 mW/cm(2) intensity of 254nm UV light. The UV light over TiO2 was more effective than 254nm UV alone in inactivating Q beta. 3.5-log(10) Q beta inactivation was achieved by UV irradiation over TiO2 suspension (10(3) mg/L) after 2 minutes of irradiation, while UV alone inactivated 2-log(10). Using a MPN-PCR method, a ca. 1-log(10)-unit decrease in Q beta RNA concentration was detected after 3 minutes of photocatalytic irradiation. The decrease was explained by damage to nucleic acid of phage Q beta due to radical oxidation, which is generated by photocatalysis.