Data di Pubblicazione:
2014
Citazione:
BIOTECHNOLOGIES FOR RESTORATION OF CULTURAL HERITAGE / E. Lombardi ; tutor: D. Daffonchio ; coordinator: D. Daffonchio. Università degli Studi di Milano, 2014 Dec 18. 27. ciclo, Anno Accademico 2014. [10.13130/lombardi-emanuela_phd2014-12-18].
Abstract:
Abstract
In recent years, operators in the restoration sector are adding to their historical-artistic competences also scientific knowledge in order to find solutions more and more effective and respectful toward the cultural heritage, the operator and the environment. Among the different scientific branches, biotechnologies allow for an innovative and precise approach to the complexity of the problems that the restorer has to face in his own daily work. Biotechnology research in the field of cultural heritage develops in two directions: on the one hand focuses on the development of accurate diagnostic techniques, useful for the correct identification and characterization of alterations and biodeteriogens; on the other hand focuses on the development of innovative restoration methods, based on the employment of new products. The employment of biotechnologies in restoration of cultural heritage is the main topic of the present PhD doctoral thesis, which deals with both of the aforementioned sides. In Chapter 1 a review on the employment of biotechnologies in the field of cultural heritage is presented, considering both diagnostic techniques for characterization of biodeteriogens, and the use of microorganisms and enzymes for restoration.
The first part of the thesis focuses on a microbial product, based on sulfate-reducing bacteria (SRB) belonging to D. vulgaris species, applied for the removal of sulfate crusts from artwork surfaces. In studies carried out in the last decades, this product has turned out to be very promising and favorable, compared to traditional restoration techniques, thanks to its capability of combining effectiveness to selectivity and safety for the restorer and the environment. Such a technology, original, innovative and sustainable, has been successfully experimented on important artworks. In Chapter 2 a review on the current knowledge of Desulfovibrio genus is presented, in particular concerning its physiology, biochemistry and biotechnological applications.
Nevertheless, the D. vulgaris-based product presented four limitations: i) low production yields and inability of long-term conservation of D. vulgaris biomass; ii) lack of an appropriate method for monitoring of abundance and activity of the biomass; iii) time-consuming application technique; iv) application limited to stone surfaces.
The overcoming of the above mentioned limitations has been the aim of the first part of the present work. A research work, structured in different phases, has been conducted for the optimization of the production process and the development of a method for the long-term conservation of the bacterial biomass (Chapter 3). Initially the laboratory protocol has been set up on small volumes at liter scale, in order to define the growth curve of the bacterium and evaluate its metabolic response to different substrates and growth conditions. subsequently the fermentative process has been transferred from the flask to 5 lt fermentor, optimizing the control of pH and H2S concentration. H2S is the main metabolic product in the fermentative process of SRB, its accumulation is toxic for bacteria, leading to unfavorable growth conditions. These improvements allowed a significant increase in biomass production, from a concentration of 1*108 cell/ml in 120h of fermentation in flask, to the concentration of 3*109 cell/ml in 72h of fermentation in bioreactor. For the long-term conservation of D. vulgaris biomass, freeze-drying has been carried out, testing the effectiveness of different cryoprotective agents. Among them, the best in terms of cell viability post-rehydration resulted to be lactose, which ensured the stability of the product for a minimum of 6 months.
Chapter 4 deals with the development of new molecular approache
Tipologia IRIS:
Tesi di dottorato
Keywords:
Biotechnology; cultural heritage; biocleaning; biodeterioration
Elenco autori:
E. Lombardi
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