Authors: A Polo F Cappitelli L Brusetti P Principi F Villa L Giacomucci G Ranalli C Sorlini
Publish Date: 2010/01/30
Volume: 60, Issue: 1, Pages: 1-14
Abstract
The study was conducted on alterations found on stone artwork and integrates microbial control and a biotechnological method for the removal of undesirable chemical substances The Demetra and Cronos sculptures are two of 12 stone statues decorating the courtyard of the Buonconsiglio Castle in Trento Italy An initial inspection of the statues revealed putative black crusts and highlighted the microbial contamination causing discoloration In 2006 the Cultural Heritage Superintendence of Trento commissioned us to study and remove these chemical and biological stains Stereomicroscopy characterised the stone of the sculptures as oolitic limestone and infrared analyses confirmed the presence of black crusts To remove the black crusts we applied a remediation treatment of sulphatereducing bacteria which removes the chemical alteration but preserves the original stone and the patina noble Using traditional and biomolecular methods we studied the putative microbial contamination and confirmed the presence of biodeteriogens and chose biocide Biotin N for the removal of the agents causing the discolouration Denaturing gradient gel electrophoresis fluorescent in situ hybridisation established that Cyanobacteria and green algae genera were responsible for the green staining whereas the black microbial contamination was due to dematiaceous fungi After the biocide Biotin N treatment we applied molecular methods and demonstrated that the Cyanobacteria and most of the green algae and dematiaceous fungi had been efficiently removed The reported case study reveals that conservators can benefit from an integrated biotechnological approach aimed at the biocleaning of chemical alterations and the abatement of biodeteriogensThe authors are grateful for the financial support of the Soprintendenza per i Beni Architettonici Trento Italy and give special thanks go to Arch Luca de Bonetti for his help throughout this research The authors also wish to thank Prof L Toniolo Politecnico di Milano for the chemical analyses
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