The Future of the Medieval Frescoes tt the Pisa Monumental Cemetery. From Extreme Rescue (1944) To Large Scale Recovery With Pioneering Innovations.

Abstract in English The presence of undesirable organic materials on the surfaces of artistic artifacts is a widespread and complex issue, often resulting from past restoration interventions. A notable example concerns the frescoes of the Monumental Cemetery of Pisa, which were damaged during the 1944 bombing and subsequently subjected to a *strappo* intervention. This process left residues of polymerized animal glue, which became difficult to remove using traditional methods. Research in the field of biocleaning has demonstrated the effectiveness of microorganisms in selectively removing organic substances without damaging painted surfaces. The UniMOL-UniMI research group selected the bacterial strain *Pseudomonas stutzeri* A29, known for its ability to degrade complex organic compounds. The treatment involved the controlled application of bacteria onto the protective canvas of the frescoes, achieving an 80-90% removal of the polymerized glue within 10-12 hours. Residual glue was eliminated using specific enzymes (protease and collagenase), followed by a buffer solution wash to remove any remaining bacterial traces. Subsequently, innovative restoration techniques were introduced, including the use of rigid *Compolam* supports, the adoption of thermoregulated sheets to prevent condensation, and a drone-based monitoring system to detect color variations on the frescoed surfaces. This intervention represented the most significant large-scale biocleaning case (approximately 1,500 m²), completed in 2018 with the relocation of the frescoes to their original walls. The multidisciplinary nature of the research highlighted the importance of integrated approaches in the field of cultural heritage, promoting sustainable methods for restoration and conservation. The combined use of biotechnology, photogrammetry, and laser scanning provided a replicable model for other artworks, contributing to the definition of scientific protocols for restoration. The project introduced technological advancements in the monitoring and documentation of the frescoes by integrating high-resolution photogrammetric surveys with terrestrial laser scanners (TLS). Image acquisition was calibrated to ensure metrically reliable restitutions, with optimized pixel density for digital printing. The use of UAVs (drones) equipped with high-resolution cameras enabled accurate documentation of the frescoed surfaces, facilitating digital conservation and the enhancement of artistic heritage. This approach represents a significant step forward in sustainable conservation, integrating advanced technologies with innovative restoration methodologies to ensure the preservation of artworks for future generations.