Study of the euendolithic activity of black meristematic fungi isolated from a marble statue in the Quirinale Palace’s Gardens in Rome, Italy

Abstract

The present study analyzed the dark patina present on the surface of a marble statue exposed in the Gardens of the Quirinal Palace in Rome, with a special focus on euendolithic black meristematic fungi. The study of the spatial distribution of microorganisms and their identification were performed by using a multistep approach based on microscopy, cultural analyses, molecular techniques, and embedding resin-casting technique. Black meristematic fungi were observed in the patina. Since morphological features are not sufficient to identify fungi belonging to this group, cultural and molecular analyses were performed. The results highlighted the presence of the species Coniosporium apollinis and of strains related to the genus Knufia (order of Chaetothyriales). The resin-casting embedding technique demonstrated the active penetration of these fungi into the marble grains, thus documenting their true endolithic behavior. The involvement of phototrophic microorganisms present on the surface in the active penetration of the marble was excluded.