Solunto archaeological park in Sicily: life under mosaic tesserae

Biodeterioration is a complex process induced by the growing and metabolic activity of a wide range of macro and microorganisms, becoming a revelling problem also for the mosaic tesserae of “Casa di Leda” in the Greco - Roman site of Solunto in Sicily. In this case-study, a thick biofilm inducing a deep alteration of mortar and consequently the mosaic tesserae detachment has been highlighted during the restoration plan. The biofilm microbial consortium has been investigated by an integrate approach based on Microscopy analysis (O.M., C.L.S.M.), in vitro culture (Nutrien and Saboraud media) and molecular biology investigation (DNA target sequence amplification, sequencing, sequence analysis). A microbial diversity has been revealed belonging to bacteria (Bacillus) and fungi (Alternaria, Aspergillus), besides cyanobacteria (Chroococcus) and green algae (Chlorella). In order to control the biofilm colonization two essential oils (EO), Thymus vulgaris and Origanum vulgare, have been utilized and their antimicrobial activity, preliminarily in vitro (agar disc diffusion methods) and after ex situ and in situ evaluated. This experimentation is aimed at identifying and implementing green biocides for the control of microbial colonization, a promising technology with a reduced impact on human health and environment, able to replace traditional biocide action.