Biocleaning on Cultural Heritage: new frontiers of microbial biotechnologies

Over the last two decades, the biotechnologies applied to Cultural heritage (CH) have become a successful novel alternative to the traditional approaches in the CH conservation and preservation. From these new perspectives, microorganisms and their metabolisms can be used for the safeguarding of artworks. Biocleaning is a field with a growing interest, based on eco-friendly processes and safe procedures, where biological reactions occurring in natural habitats are optimized in artificial conditions with the aim of CH conservation. This represents a new tool and opportunity for the development and improvement of the sector, with a great advantage for the CH conservation-restoration, in terms of safety, effectiveness, costs and environmental sustainability. This review focuses on the use of microbes and enzymes involved in biocleaning of CH artworks. The aim is to provide a comprehensive, critical and chronological view of the scientific works published until now where ‘virtuous’ microorganisms are applied on different CH materials, pointing out strength and drawback of the biocleaning treatments.     

Biotechnology applied to cultural heritage: biorestoration of frescoes using viable bacterial cells and enzymes

AIMS: To set up and employ, for the biorestoration of cultural heritage (altered frescoes), an advanced and innovative biotechnology method based on the sequential use of whole viable bacterial cells and specific enzymes. METHODS AND RESULTS: The bioremediation intervention consisted of the direct application onto an artwork surface of whole bacterial cells of the Pseudomonas stutzeri A29 strain (bioaugmentation), followed by, in a final step, a purified Protease enzyme. The bioremediation was performed on a Spinello Aretino fresco that had become altered by the animal glue residues of past restoration. For the reader's interest the fresco is the 14th century Conversione di S. Efisio e battaglia (Conversion of S. Efisio and battle), size 3.5 x 7.8 m at the Pisa Camposanto Monumentale, Italy. An assessment was made of the final costs of the biological tests (whole bacterial cells, enzymes) so as to compare them with other intervention techniques. CONCLUSIONS: A successful innovative biological approach to recover valuable frescoes was set up, and the best conditions for treatment efficiency were identified. Furthermore the cost of the biological cleaning using viable bacterial cells and enzymes (P. stutzeri, Protease, Collagenase, 1 : 3 : 10, ratio respectively) was much lower than that of other conventional methods, making this biotechnology not only very interesting but also very competitive. SIGNIFICANCE AND IMPACT OF THE STUDY: New biotechnologies with an innovative, soft approach to the 'biocleaning' and 'biorestoration' of cultural heritage are in constant demand, and our results are clear evidence that such an approach has been achieved; the technique could be of significant importance towards developing other goals.