Bioconsolidation potential of indigenous microbial communities in hypogeal environments

Microbial-Induced Calcium Carbonate Precipitation (MICP) is a natural biological process involving bac- teria that promote the formation of calcium carbonate. This process has shown promising results in a wide range of technological applications, including in the field of cultural heritage, where one of the major challenges is conserving and protecting mural paintings in hypogeal environments, which are char- acterized by high humidity and low light levels. In such environments, deterioration of the plaster can compromise the integrity of the pictorial surface. This study explores the potential for calcium carbonate precipitation and the dynamics of indigenous microbial communities associated with the wall surfaces and calcarenite rock of the Etruscan tomb of Tarquinia, Tomba Maggi . The microbial consortia were culti- vated under different nutrient conditions to assess their capacity for calcium carbonate biomineralization and the bacterial phylum enrichment. Results from SEM-EDX and XRD analyses confirmed the formation of biogenic calcite under laboratory conditions. High-throughput sequencing revealed consistent enrich- ment of carbonatogenic taxa, particularly within the Bacillota phylum. These results suggest that activat- ing resident microbial communities in situ —rather than applying exogenous strains —is a viable and ecologically compatible strategy for bioconsolidating the hypogeal tombs at the UNESCO necropolis of Tarquinia.