Biodeterioration Patterns and Their Interpretation for Potential Applications to Stone Conservation: A Hypothesis from Allelopathic Inhibitory Effects of Lichens on the Caestia Pyramid (Rome)

Abstract

The colonisation of stone by different organisms often leaves biodeterioration patterns (BPs) on the surfaces even if their presence is no longer detectable. Peculiar weathering patterns on monuments and rocks, such as pitting phenomena, were recognised as a source of information on past colonisers and environmental conditions. The evident inhibition areas for new bio-patinas observed on the marble blocks of the Caestia Pyramid in Rome, recognisable as tracks of previous colonisations, seem a source for developing new natural products suitable for restoration activities. To hypothesise past occurring communities and species, which gave rise to such BPs, we carried out both in situ observations and analyses of the rich historical available iconography (mainly photographs). Moreover, we analysed literature on the lichen species colonising carbonate stones used in Roman sites. Considering morphology, biochemical properties and historical data on 90 lichen species already reported in Latium archaeological sites, we suppose lichen species belonging to the genus Circinaria (Aspicilia s.l.) to be the main aetiological agent of such peculiar BPs. These results seem relevant to highlight the long-lasting allelopathic properties of some lichen substances potentially applicable as a natural product to control colonisation, improving the environmental and economical sustainability of stone restoration.

Analysis of Biodeteriogens on Architectural Heritage. An Approach of Applied Botany on a Gothic Building in Southern Italy

“…Mortar porosity allows the penetration of water and soluble salts coming from the masonry materials themselves [70] and the external adjacent embankments, increasing the susceptibility of the stone surface and creating good indoor conditions for the establishment and development of microbial biofilms. Results showed that the samples collected from the internal walls of our study site included a wide range of microorganisms found in environments characterized by almost constant temperatures throughout the year and quite high humidity levels, such as caves [71], hypogea [72], and grottoes [73]. In order to provide information on the diversity of biofilm microorganisms, the combination of molecular techniques with culture-dependent methods has been used for the first time in the study area.…”

Preliminary Studies on Fungal Contamination of Two Rupestrian Churches from Matera (Southern Italy)

“…The control of fungi in cultural heritage assets is an important issue which was investigated using various ways to limit their development and growth such as the use of natural substances employed as green conservation strategies and the utilization of engineered nanomaterials [67][68][69].…”

Holistic Approach to the Restoration of a Vandalized Monument: The Cross of the Inquisition, Seville City Hall, Spain

“…(e.g., Caloplaca chalybaea) was an unknown taxon of Trebouxia, typical of the Mediterranean area. These three lichens (among others) identified in the City Hall were also found on natural limestone outcrops, buildings and monuments [58][59][60][61][62]. ON479853 Fungi * Lichens are taxonomically classified by their fungal partner, so all lichens belong to the Fungi kingdom.…”