The colonialisation of paint films by microorganisms in the UK and Norway
This work was undertaken in order to study the colonisation of paint films by microorganisms. Quantitative data derived from a range of analytical techniques has provided information on surface changes occurring in the paint films during colonisation in the field and during laboratory exposure experiments. Exposure trials, took place at four different sites, two in Norway and two in the UK. The sites were situated in Sandeflord and Bergen and in Preston and Blackley near Manchester, with the panels facing North at an angle of forty-five degrees. The results obtained from these studies indicate that the range of microorganisms found on the panels exposed at the locations were very similar, suggesting that there was no great difference encountered in the airborne flora as indicated by settle plates at the sites investigated. Painted panels made from Spruce were found to be more heavily colonised than those made from calcium silicate or aluminium. The formulation biocide was seen to be effective in the vermiculite bed system against Aureobasidium pullulans. The Scanning Electron Microscope (SEM) and Environmental Scanning Electron Microscope (ESEM) provided visual evidence that in the case of Aureobasidium pullulans, fungal hyphae penetrated the paint film by the dissolution of the paint binder rather than disruption of the paint films by the growth of microorganisms through the paint film from below. Spruce panels that had been gamma irradiated showed a similar surface colonisation pattern to those untreated. Matrix Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry(MALDI TOF MS) showed that the technique was able to distinguish between spectra generated by different genera of fungi and between spectra generated by different species of the same genus. It is considered that the technique may provide evidence to confirm or refute the nominally common taxonomic status of fungal isolates from different sites. The work undertaken using the Talysurf"Im, shows that the technique is suitable for detecting changes in the surface topography of unprotected paint films. The results from work undertaken with films that had been subject to prolonged exposure at the Preston site and within a vermiculite bed system confirm this. Comparisons of the Fourier transform infrared spectroscopy (FTIR) spectra obtained for exposed and non-exposed paint films suggested that the exposure had no effect on the overall composition of the paint film.