Studies on bacterial calcium carbonate precipitation for stone conservation

Calcium carbonate precipitation is a very diffuse phenomenon among bacteria not restricted to any specific group or environment. A new approach to conservative treatment of calcareous stones was suggested in the last years by exploiting this natural process. Application of bacterial cultures can induce calcite precipitation inside stone porosity conferring a consolidation effect by a natural material similar to that of the substrate. However the use of viable bacteria could give some drawbacks due to general microbial growth promoted by the application of organic nutrients on monumental stone. Our aim is to develop a cell free bacteria-mediated system able to induce CaCO3 mineral formation inside stone porosity. To achieve this, we are studying calcite crystal formation in Bacillus subtilis by different experimental approaches, both in vitro and in vivo, directed to identify genes, molecules and cell structures involved in the biomineralization process.