Molecular Diagnostics and Determining of Biodeterioration Risk for the 16th Century Icon “Descent into Hell” from the State Tretyakov Gallery

Various heritage objects can be subjected to various types of biodegradation and biodeterioration. Mold fungi can destroy many types of art—be it monumental art or easel paintings. Tempera paintings on wood are at risk of biodeterioration, since the wide variety of organic and inorganic materials in art objects often provide an optimal habitat for biological colonization, causing aesthetic and structural damage. In this regard, timely identification and characterization of their microbiological destructive potential are critical. The fungi Syncephalastrum sp. STG-160 and Cladosporium sphaerospermum STG-161, isolated from bio-lesion sites of the 16th century icon “Descent into Hell” from State Tretyakov Gallery, Moscow, were identified and characterized morphologically and molecularly in our work. Syncephalastrum sp. was found in an unusual habitat that has not been previously described for this species. To determine the biodegradability of the identified fungi, their cells were inoculated onto mock layers—egg yolk ochre, cobalt green tempera pigments, and watercolor black. The results show that some pigments were more degradable than others. The addition of cobalt green completely inhibited STG-161 growth and significantly deceleratedSTG-160 mycelium development, most likely due to the presence of heavy metal ions in the pigment. Ochre, a frequently used pigment in restoration practice, is the most degradable material for Syncephalastrum sp. STG-160. Combining culture-dependent methods with SEM and fluorescence microscopy allowed us to identify an invisible individual spore of Syncephalastrum sp. STG-160 and a single hypha of Cladosporium sphaerospermum STG-161 directly on the icon’s surface in clean-contaminated zones, potentially allowing their development in cases of adverse temperature and humidity conditions. Therefore, in order to ensure rapid and effective conservation, it is crucial to assess and quantify the presence of biological systems causing damage to the heritage object itself as well as its individual art components.