Interactions of fungi with titanium dioxide from paint coating

Field emission scanning electron microscopy coupled with energy dispersive X-ray spectroscopy analysis of white-painted gypsum panels incubated for 11 months with either a consortium comprising several fungal species or their monocultures demonstrated that spores of Penicillium minioluteum concentrated titanium, a common white paint ingredient. The paint coating was severely degraded and the exposed underlying gypsum seen was to be contaminated with fungal spores. Ulocladium atrum, while growing well on consortium-inoculated panels over 12 weeks, failed to remain the principal colonizer after 11 months and did not concentrate minerals on its spores nor show visible degradation of the coating. When inoculated in pure culture, U. atrum failed to thrive on the panels, its concentration, measured as ergosterol, falling after 21 days. U. atrum, previously reported to be the major surviving fungus after the 12-week incubation based on the British Standard test BS3900 for fungal growth on paint, has discolouring but not degrading effects and probably grows on the paint coating at the expense of organic matter, including that originating from other fungal species. Ulocladium consortiale, a strain that grew on stored uninoculated panels, caused paint coating degradation visible under field emission scanning electron microscopy and detected as reduction in titanium in the underlying paint coating; however, it did not concentrate any particular elements on its spores.