Art-loving bugs: The resurrection of Spinello Aretino from Pisa's cemetery

Dry biocleaning of artwork: an innovative methodology for Cultural Heritage recovery?

An innovative methodology is proposed, based on applied biotechnology to the recovery of altered stonework: the “dry biocleaning”, which envisages the use of dehydrated microbial cells without the use of free water or gel-based matrices. This methodology can be particularly useful for the recovery of highly-ornamented stoneworks, which cannot be treated using the conventional cleaning techniques. The experimental plan included initial laboratory tests on Carrara marble samples, inoculated with dehydrated Saccharomyces cerevisiae yeast cells, followed by on-site tests performed on “Quattro Fontane” (The Four Fountains), a travertine monumental complex in Rome (Italy), on altered highly ornamented areas of about 1,000 cm². The mechanism is based on the spontaneous re-hydration process due to the environmental humidity and on the metabolic fermentative activity of the yeast cells. Evaluation by physical-chemical analyses, after 18 hours of the biocleaning, confirmed a better removal of salts and pollutants, compared to both nebulization treatment and control tests (without cells). The new proposed on-site dry biocleaning technique, adopting viable yeast cells, represents a promising method that can be further investigated and optimized for recovering specific altered Cultural Heritage stoneworks.

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.

The Potential Use of Microorganisms as Restorative Agents: An Update

The biodeterioration process involves every type of Cultural Heritage item, including monuments, stoneworks, frescoes, and easel paintings. The accurate study of the microbial and fungal communities dwelling on artworks, and involved in their deterioration, is essential for the adoption of optimal prevention and conservation strategies. Conventional restorative methods, that usually involve chemical and physical technologies, present some disadvantages, including short-term and unsatisfactory effects, potential damage to the treated works, human toxicity, and environmental hazards. Research in the field of restoration has paved the way for innovative biological approaches, or ‘biorestoration’, in which microorganisms are not only considered as an eventual danger for artworks, but rather as potential tools for restoration. The present review describes the main aspects of the biodeterioration process and highlights the most relevant biorestoration approaches: bioconsolidation, biocleaning, biological control, and new promising bio-decontaminating compounds.

Onsite advanced biocleaning system for historical wall paintings using new agar-gauze bacteria gel

AIMS

This study reports the results of the application of a new agar-gauze biogel system activated with viable bacterial cells to altered wall paintings.

METHODS AND RESULTS

Biocleaning using agar biogel and agar-gauze biogel systems was performed onsite by direct application to altered wall painting surfaces (25-1000 cm² ). The treatments were performed for the restoration of two original Italian sites: (i) at the Vatican Museums, Cristo che salva Pietro dalle acque-La Navicella, a wall painting by Giovanni Lanfranco (1627-1628) and (ii) at Pisa Cathedral Cupola, Incarnato, a wall painting by Orazio Riminaldi (1593-1630) and his brother Girolamo Riminaldi. The novelty of this study is the use of viable Pseudomonas stutzeri A29 cells in an advanced agar-gauze biogel system and the short bio-application contact times of between 3 and 12 h. The historical artworks were altered by lipid and protein residues from past restoration, as confirmed by Py-gas chromatography-mass spectrometry and FT-IR data. The effectiveness of the biological treatment was assessed, and general considerations were discussed.

CONCLUSIONS

The short bio-application contact time of advanced agar-gauze gel activated with viable P. stutzeri cells makes this biotechnology promising as an alternative method to the traditional onsite cleaning techniques currently in use for altered historical wall paintings.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, we report for the first time the biocleaning of altered materials located in vertical and vaulted areas using agar-gauze biogel with short application times. These findings are of great significance for future restoration activities and are crucial for determining the best preservation strategies in this field.

Application of Microbial Cleaning Technology for Removal of Surface Contamination

Microbial cleaning takes advantage of naturally-occurring microbes to remove a wide variety of contaminants from various surfaces. The method is based on the affinity of microbes for hydrocarbons that are digested, producing harmless carbon dioxide, water, and soluble fatty acids. The microbes are nonpathogenic and are safe to handle and dispose. The process is environmentally-friendly and is less expensive than solvent cleaning, but it is not applicable to high precision cleaning applications. Typical applications include parts washing; oil and grease removal from concrete and other floor surfaces, and from drains and grease traps; cleaning and disinfection in healthcare facilities; cleaning of historical artworks and structures; and household and institutional cleaning applications.

Stenotrophomonas maltophilia SeITE02, a new bacterial strain suitable for bioremediation of selenite-contaminated environmental matrices

Biochemical and proteomic tools have been utilized for investigating the mechanism of action of a new Stenotrophomonas maltophilia strain (SeITE02), a gammaproteobacterium capable of resistance to high concentrations of selenite [SeO(3)(2-), Se(IV)], reducing it to nontoxic elemental selenium under aerobic conditions; this strain was previously isolated from a selenite-contaminated mining soil. Biochemical analysis demonstrated that (i) nitrite reductase does not seem to take part in the process of selenite reduction by the bacterial strain SeITE02, although its involvement in this process had been hypothesized in other cases; (ii) nitrite strongly interferes with selenite removal when the two oxyanions (NO(2)(-) and SeO(3)(2-)) are simultaneously present, suggesting that the two reduction/detoxification pathways share a common enzymatic step, probably at the level of cellular transport; (iii) in vitro, selenite reduction does not take place in the membrane or periplasmic fractions but only in the cytoplasm, where maximum activity is exhibited at pH 6.0 in the presence of NADPH; and (iv) glutathione is involved in the selenite reduction mechanism, since inhibition of its synthesis leads to a considerable delay in the onset of reduction. As far as the proteomic findings are concerned, the evidence was reached that 0.2 mM selenite and 16 mM nitrite, when added to the culture medium, caused a significant modulation (ca. 10%, i.e., 96 and 85 protein zones, respectively) of the total proteins visualized in the respective two-dimensional maps. These spots were identified by mass spectrometry analysis and were found to belong to the following functional classes: nucleotide synthesis and metabolism, damaged-protein catabolism, protein and amino acid metabolism, and carbohydrate metabolism along with DNA-related proteins and proteins involved in cell division, oxidative stress, and cell wall synthesis.

Applied microbiology and biotechnology in the conservation of stone cultural heritage materials

The contribution of applied microbiology and biotechnology for the preservation and restoration of culturally relevant stoneworks has been used only to a minor extent. Until recently it only involved the identification of the living organisms accountable for the deterioration of those materials by classic phenotypic identification methods. This seems to be changing, given the amount of work recently published that focuses in the introduction of molecular-based techniques for the detection of microorganisms in historic stone. Such techniques complement and expand the information up till now gathered by conventional identification methods. Along with this, efforts are being made to develop and implement bio-based methodologies that may actively contribute to the bioremediation of weathered historic stoneworks. The present mini-review aims to provide an overview of recent findings on these matters.

Biology of Pseudomonas stutzeri

Pseudomonas stutzeri is a nonfluorescent denitrifying bacterium widely distributed in the environment, and it has also been isolated as an opportunistic pathogen from humans. Over the past 15 years, much progress has been made in elucidating the taxonomy of this diverse taxonomical group, demonstrating the clonality of its populations. The species has received much attention because of its particular metabolic properties: it has been proposed as a model organism for denitrification studies; many strains have natural transformation properties, making it relevant for study of the transfer of genes in the environment; several strains are able to fix dinitrogen; and others participate in the degradation of pollutants or interact with toxic metals. This review considers the history of the discovery, nomenclatural changes, and early studies, together with the relevant biological and ecological properties, of P. stutzeri.

The role of biotechnology in art preservation

Biotechnology has played a key role in medicine, agriculture and industry for over 30 years and has advanced our understanding of the biological sciences. Furthermore, the tools of biotechnology have a great and largely untapped potential for the preservation and restoration of our cultural heritage. It is possible that these tools are not often applied in this context because of the inherent separation of the worlds of art and science; however, it is encouraging to see that during the past six years important biotechnological applications to artwork preservation have emerged and advances in biotechnology predict further innovation. In this article we describe and reflect upon a unique example of a group of scientists and art restoration technicians working together to study and treat of a piece of colonial art, and review some of the new applications in biotechnology for the preservation of mankind's cultural heritage. We predict an expansion in this field and the further development of biotechnological techniques, which will open up new opportunities to both biologists and artwork preservers.