Microbial recolonization of the mural paintings after restoration in the Etruscan Tomba degli Scudi in Tarquinia

The protection and preservation of frescoes in hypogeal environments is an extremely complex field, stable humidity and temperature favour the presence and development of complex microbial communities. Thus, studying their role in the biodeterioration of frescoes is essential for implementing conservation strategies. The Etruscan tombs of Tarquinia hold a specific microbial community that, over the centuries, produced a white patina that covered the surfaces of these hypogeal environments. This patina is formed by a peculiar nanostructure of calcium carbonate, called moonmilk, and represents a unique case of bio-colonization that contributed to the protection of mural paintings rather than to their biodegradation. The removal of this patina is necessary to make the paintings usable, not only to admire their beauty, but also for their study. Nevertheless, the removal of the moonmilk from the Tomba degli Scudi triggered rapid microbial growth. Here, we report the results of a microbiological survey of the atrium mural paintings from the restoration of 2016 to now.