Protection and Consolidation of Stone Heritage by Bacterial Carbonatogenesis

For millennia, artists and architects around the world used natural stone for the carving of sculptures and the construction of monuments, such as Roman, Greek, and Maya temples, the European cathedrals, and the Taj Mahal, just to name a few. Currently, the survival of these irreplaceable cultural and historical assets is under threat due to their continued degradation caused by various biotic and abiotic weathering processes that affect not only the aesthetic appearance of these structures, but also their durability and survival. The natural precipitation of calcium carbonate minerals by bacteria has been proposed for conservative interventions in monument restoration. This chapter reviews the application of biomineralization by (indigenous) bacterial carbonatogenesis as a novel technology for the protection and consolidation of altered ornamental materials. Carbonatogenesis is based on the ability of some bacteria to induce calcium carbonate precipitation. Laboratory and in situ results support the efficacy of bacterial carbonatogenesis, since remarkable protection and consolidation are achieved on the surface and in depth, without alterations in color or porosity, and without fostering the development of microbiota that could be harmful to the stone material. A discussion on the advantages of this novel biotechnology is provided. Challenges and future work on bioconsolidation of stone artifacts are also outlined.