Mechanism of the photocatalytic inactivation of Lactobacillus casei phage PL-1 by titania thin film

The mechanism of the inactivation of Lactobacillus casei phage PL-1 suspend ed in a phosphate buffer by black-light (BL) -catalytic titanium dioxide (T iO2) thin film was studied. Generation of both superoxide anions (O-2(-)) a nd hydroxyl radicals (. OH) was confirmed in the aqueous medium in which Ti O2 film was settled with BL irradiation under gentle shaking. With BL-irrad iation alone without TiO2 film, only O-2(-) was generated to some extent. T he genome DNA inside the phage particles was found to be fragmented by the treatment of PL-1 phages with BL-catalytic TiO2 film. The phage inactivatio n by BL-catalytic TiO2 film was inhibited by the addition of albumin in a c oncentration-dependent manner. BL-catalytic TiO2 film was considered to cau se primarily the damage to the capsid protein through the generation of act ive oxygen species such as . OH, followed by damage to the genome DNA insid e the phage particles.