Identifying the role of reactive oxygen species (ROSs) in Fusarium solani spores inactivation

The inactivation mechanism of photocatalytic disinfectants on bacteria is well known. In contrast, the potential inactivation of fungal spores by visible-light induced photocatalysis has been recognized, but the inactivation mechanism is poorly understood. We hypothesize that photocatalytically generated reactive oxygen species (ROSs) are directly involved in this mechanism. To test this hypothesis, we identified the roles of ROSs in the inactivation of Fusarium solani spores. As the photocatalysts, we doped TiO(2) with 3 typical dopants, forming Ag/TiO(2), N/TiO(2) and Er(3+):YAlO(3)/TiO(2). The Ag/TiO(2) photocatalysis was dominated by H(2)O(2), with the longest lifetime among the investigated ROSs. Ag/TiO(2) photocatalysis yielded almost 100 % inactivation efficiency and preserved the cell-wall shape of the spores, thus minimizing the biomolecule leakage. Er(3+):YAlO(3)/TiO(2) was dominated by h(+) ROSs, yielding an inactivation efficiency of 91 %; however, the severe leakage released large numbers of molecular bio-products. Severe damage to the cell walls by the h(+) species was confirmed in micrograph observations. Subsequent to cell wall breakage, the Er(3+):YAlO(3)/TiO(2) nanoparticles entered the spore cells and directly oxidized the intracellular material. The N/TiO(2) photocatalysis, with •O(2)(−) dominated ROSs, delivered intermediate performance. In conclusion, photocatalysts that generate H(2)O(2)-dominated ROSs are most preferred for spore inactivation.