White fungal covering on the wall paintings of the Saint-Savin-sur-Gartempe Abbey church crypt: A case study

The crypt of Saint-Savin-sur-Gartempe Abbey church contains a notable example of Romanesque wall paintings. A recurrent white fungal covering has affected these wall paintings since the late 1970s. Its composition and changes were studied from 2005 to 2015 through microbial isolations, ATP activity measurements and antimicrobial susceptibility testing. ATP monitoring showed that the fungal activity level remained high throughout the ten years, with spatial and temporal variations over time. Engyodontium album was the main agent isolated from the fungal covering, showing change in fungal strains compared to those isolated before 2005. This change in the fungal community could result from the previous application of econazole nitrate as a biocidal product. However, multiple susceptibility tests showed a possible variation of active ingredients that could lead to the successful elimination of the fungal contamination. Alternative solutions for the preservation of the wall paintings against fungal covering are discussed.