Enzymatic laundry for old clothes: immobilized alpha-amylase from Bacillus sp. for the biocleaning of an ancient Coptic tunic
The classification and conservation of ancient artworks (belonging to collections) is of important cultural, historical, and economic concern. However, ancient textiles often display structural damage that renders them fragile and unsuitable for exhibition. One of the most common types of damage is linked to erroneous restoration treatments, among which the application of glues to consolidate cuts. Harsh strategies, such as mechanical or chemical treatments, are not suitable since they can cause further impairment of the fabric, whereas mild approaches, like wet cleaning, are often ineffective, as also demonstrated by the present study. Here, we have explored the possibility of using gellan-immobilized enzymes of bacterial origin (Bacillus alpha-amylase) to obtain a satisfactory starch removal from a damaged archaeological tunic-shroud from the Turin Egyptian Museum (Italy), without altering the original yarns or textile fibers. This method, already applied to clean casein-damaged wall paintings, as well as cotton, silk, and linen fabrics, has proved to be optimal for the treatment of a wool burial shroud and to be able to definitively solve fragile textile restoration problems. Moreover, efforts have been made to obtain insights into the artwork: a multidisciplinary approach has allowed to obtain a correct chronological attribution (radiocarbon dating) and fabric fiber characterization (SEM-EDX) as well as shed light on the colored parts and dark stains (FORS+IRFC and XRF). Finally, the evaluation of the type of glue, by Fourier transform infrared spectroscopy, has suggested the best enzyme for glue removal. These results have demonstrated that a mild bio-based approach is a successful tool for the treatment of archaeological textiles in critical conditions.
KeywordsAlpha-amylases Gellan-immobilized bacterial enzymes Biorestoration Archeological textile SEM-EDX FT-IR
The present study is an extension of the Master thesis in Conservation and Restoration of Cultural Heritage of the University of Turin (Ferrari 2013) which won the IGIIC Award for the Best Thesis in Conservation and restoration of Cultural Heritage 2014. We would like to thank the textile restorer Susanna Conti for her technical suggestions, the Egyptologist Rosa Boano for her contribution on the historical aspects, and Primo Brachi for his fiber deterioration interpretation. Special thanks are due to Daniele Demonte for the IRFC analyses and photographic documentation. Particular thanks to Monica Gulmini for her helpful suggestions and to all the technicians of the scientific laboratories of the Restoration and Conservation Centre “La Venaria Reale” (Turin). We are indebted to Alessandro Lo Giudice and Alessandra Romero for encouraging this project.
Compliance with ethical standards
This work was supported by a research project of Turin University, the Egyptian Museum of Turin and the Restoration and Conservation Centre “La Venaria Reale.”
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors. No strain deposited in a public strain collection has been employed in this study.
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