Micro-organisms love art - The discovery and identification of harmful micro-organisms in wall-paintings

Vienna (Austrian Science Fund) - Historical wall-paintings are a favourite abode for micro-organisms such as fungi, bacteria or algae. The colour pigments and fixatives in the paintings provide an ideal breeding ground for the spread and growth of these harmful populations. The restorers are largely helpless in the face of this phenomenon. With the support of the Austrian Science Fund, Werner Lubitz from the Institute for Microbiology and Genetics of the University of Vienna and his team are using gene technology as a new method for discovering and identifying these unwelcome guests. Thanks to the new method of analysis, even micro-organisms which were previously impossible to trace can now be tracked down. As a result, appropriate restoration methods can now be used to put up an effective fight against these infestations.

Discolouration, stains and crumbling of the pigmentary layer - these are the serious consequences of a micro-organism infestation in a wall-painting. And yet not all of these pests can be discovered through the use of the traditional and extremely expensive methods of investigation, such as the electron microscope. However, the system developed by Lubitz is offering restorers completely new strategies in the fight against these micro-organisms. "We track down the micro-organisms in the wall-painting material directly, by taking small samples and using the bacterial DNA sequences contained in them for the analysis. The genetic information can then be used to draw conclusions about the symbiosis of the micro-organisms and their possible damage potential can be determined by examining the relationship to known representatives of these micro-organisms. The main difficulty involved in this work is the fact that so few micro-organisms (less than 0.1%) are known," says Lubitz in explanation of his method. A particular advantage of his method is that it only requires very small samples. Important paintings can therefore be optimally preserved. This innovative approach also means that there is no longer any need for the expensive process of cultivating the micro-organisms in the laboratory.

Successful project at Herberstein Castle
Lubitz has already applied his method to a wide range of wall-paintings, such as in St. Catherine's Chapel at Herberstein Castle in Styria. The wall-paintings there, which date from the 14th century, had developed a pink discolouration. The reason for this was that a certain type of micro-organism had infested the work of art and it was thanks to Lubitz's method that this micro-organism was successfully discovered for the first time. Lubitz and his colleagues Sabine Rölleke, Guadalupe Pinar and Claudia Gurtner have also been successful in Carmona in Spain and in Lower Saxony. Lubitz has also tested his analysis method on glass and ceramics in cooperation with the Institute for Glass and Ceramics at the University of Nuremberg. "The historic glass in Stockkämpen church dates from the year 1870 and had also fallen prey to the micro-organisms," he explains. The prehistoric caves of Altamira, Llonin, La Garma and Tito Bustillo in Northern Spain are a further important area of application for the Lubitz method. In all these places, Lubitz found micro-organisms, whose existence in paintings of this kind had previously been considered to be practically impossible.

Prof. Dr. Werner Lubitz
University of Vienna, Institute for Microbiology and Genetics
T 01 4277 54670

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