Stone restoration via bacterial denitrification

Through time, our built cultural heritage has been compromised due to the effects of weathering. Fluids are a major driver of weathering by triggering dissolution and precipitation and playing an important role in frost and salt damage. As a result, masonry turns damaged and disaggregated. To impact these processes, fluid flow in the pore network of the material can be manipulated.

Microorganisms are capable of attaching to rock surfaces and live inside the pore system. Their presence and metabolites can influence structural porosity and composition. Bacterial phenomena such as bioclogging, biocement, and biogas production alter at the pore scale: the fluid flow, moisture, freezing-thawing weathering, roughness, and wettability.

Paracoccus denitrificans performs a complete denitrifying metabolism linked to the wanted phenomena. Denitrification can be engineered with the ultimate aim of generating Nitrogen bubbles and Microbial Induced Calcite Precipitation (MICP). While, the combined microbial colonization can lead to the formation of biofilms that positively prevent the freezing-thawing weathering in the porous network. The sequence of biochemical reactions in denitrification is a harmless bioprocess that promises an added value in porous media applications and specifically for stone conservation.