The effect of anatase and rutile crystallites isolated from titania P25 photocatalyst on growth of selected mould fungi

Antifungal properties of anatase and rutile crystallites isolated from commercial titania P25 photocatalyst were investigated by mycelium growth in the dark and under indoor light. Investigated fungi, i.e., Pseudallescheria boydii, Scedosporium apiospermum, Pseudallescheria ellipsoidea, Scedosporium aurantiacum, Aspergillus versicolor, Aspergillus flavus, Stachybotrys chartarum, Penicillium chrysogenum, Aspergillus melleus, were isolated from air and from moisture condensed on walls. Anatase and rutile were isolated from homogenized P25 (homo-P25) by chemical dissolution, and then purified by washing and thermal treatment. For comparison, homo-P25 was also thermally treated at 200 degrees C and 500 degrees C. Titania samples were characterized by X-ray diffractomety (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS) and scanning transmission electron microscopy (STEM). It was found that properties of titania, i.e., band-gap energy, impurities adsorbed on the surface, nanoparticle aggregation, and kind of fungal structure, highly influenced resultant antifungal activities. It is proposed that some fungi could uptake necessary water and nutrient from titania surface. It was also found that even when differences in mycelium growth were not significant, the sporulation and mycotoxin generation were highly inhibited by light and presence of titania. (C) 2015 Elsevier B.V. All rights reserved.