Applications of bacterial carbonatogenesis to the protection and regeneration of limestones in buildings and historic patrimony

Abstract The ability of the so-called carbonatogenic bacteria may be used for producing surficial protecting coatings (biocalcin) on limestones buildings, monuments and statuary. This is the concept of biomineralisation. Laboratory experiments were undertaken in order to choose the most active bacterial strains and to improve the composition of the nutritional media suitable for stimulating the nitrogen cycle metabolic pathways which are the only ones to be used in aerobic and/or microaerophilic conditions. Life-size experiments, subsequent measurements, and observations show that this natural process of biomineralisation is feasible within the frame of industrial constraints. This concept of further developments includes the creation of patinas and the manufacturing of biological mortars and cements which were also improved in the laboratory. The biomineralisation recreates a material that is remarkably similar to the limestone substrate because it uses natural microbial mediation which follows the same natural processes that formed many limestones.