Laboratory and field studies on thin paint films

An account is presented of some aspects and results of a collaborative project currently being undertaken as part of the European Collaborative Action COST 520 programme in Working Group 3. The project involves the response of biocide- and non-biocide-containing thin paint films to microbial colonisation under laboratory and field conditions. From the results of exposure studies at four sites, two in the UK and two in Norway, it was found that some microorganisms were common to both locations. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI TOF MS) was used in a novel way to establish characteristic mass spectral fingerprints of different fungal genera and different species of the same fungal genus. The results show that databases can be produced which provide convincing evidence for the application of this technique in taxonomy. Scanning electron microscopy was used to visualise Aureobasidium pullulans colonising the paint film. Evidence of hyphal penetration and disruption of the paint binder is suggested. Surface roughness measurement was used to investigate the effect of exposure on the surface topography of the paint. It was found that changes in the surface roughness increased over the duration of the experiment. Fourier transform infrared spectroscopy was used in the reflectance mode to detect chemical changes in the surface of the paint film. It was found that no positional or absorbance changes in the spectrum of the paint film were detected as a result of inoculating the film in a vermiculite bed system. However, some spectra did suggest that surface changes had occurred as a result of a reduction in diffuse scattering from the surface.