Paola Cennamo

This study investigates the biodeterioration of mosaic surfaces in a semi-confined archaeological environment along the Phlegraean coast (Baiae, Italy), focusing on the interaction between salt efflorescence and phototrophic biofilms. A multi-analytical approach was employed, integrating in situ observations with ex situ analyses, including SEM/EDS, FTIR spectroscopy, and metabarcoding (16S and 18S rRNA), to characterize both abiotic and biotic alteration patterns. Results highlight subtle traces of spatial differentiation: samples from the more exposed sector showed a more consistent colonization by halotolerant and halophilic taxa, particularly among Halobacteria and Rubrobacter, along with abundant sodium, chloride, and sulfate signals suggestive of active salt crystallization. Protected areas exhibit a comparable presence of salts with less diverse halophilic communities that vary along a vertical gradient of light exposure. The integration of chemical and biological data supports a model in which salt stress and biofilm development are co-dependent and synergistic in driving surface degradation. These findings emphasize the need for context-specific conservation strategies that account for the combined action of environmental salinity and microbial communities on historical materials.

The conservation of cultural heritage has long garnered significant attention within the scientific community, particularly due to the biodeterioration processes driven by microbial colonization. These processes can severely compromise the aesthetic, chemical, and physical integrity of artworks. While traditional chemical biocides are widely used, they present notable drawbacks, including toxicity, chemical instability, and the risk of inducing microbial resistance. Accordingly, efforts to expand the repertoire of molecules with biocidal activity are of utmost significance. In this study, we report the synthesis and characterization of selenium-based biocides with biocidal activity. Characterization was performed using NMR spectroscopy and gas chromatography–mass spectrometry (GC-MS). The biocidal efficacy of these compounds was evaluated via algal growth inhibition tests (OECD 201), employing Raphidocelis subcapitata as a model organism. Our results indicate that certain seleno-sugars exhibit a dose-dependent inhibition of algal growth, suggesting superior biocidal activity compared to conventional agents. Notably, one compound demonstrated an optimal balance of efficacy and chemical stability and was selected for subsequent in vivo testing.

The deterioration of stone heritage in urban environments is mainly the product of sources of air pollution like vehicular traffic and domestic heating. The results of these phenomena usually manifest as acid rain and particulate patinas, acting on the surface of stone monuments to form the so-called “black crusts”, a typical stone degradation product, mainly composed of gypsum. The aims of this study were to investigate the extent of these phenomena on the decorative apparatus of the frontal façade of Gesù Nuovo Church, in the historical centre of Naples (Italy). Preliminary diagnostics consisted of XRD and FTIR to analyse the composition of stone materials and inquire about previous restorations. The chemical characterization of black crusts was performed, using a diverse array of techniques, to highlight how different compounds are distributed along a vertical gradient and considering the proximity of specific sources of pollution (vehicle engine ignition, incense combustion, domestic heating products). Finally, molecular biology techniques were employed to identify the organisms which typically dwell in this formation and speculate about their contribution to the degradation of stone.

Campanula fragilis Cirillo is a species distributed in central and southern Italy and includes two subspecies with uncertain taxonomic position and distribution. By means of nuclear and chloroplast markers, we attempted at testing the genetic distinctness of the two subspecies, as well as their possible correspondence with geographical or ecological patterns. After a revision of geographic occurrences based on herbarium data, we carried out species distribution modeling to assess the present and future distribution of this species under different ecological variables, also for conservation purposes. Our findings support the recognition of two weakly differentiated taxa, here accepted at subspecific rank, in agreement with the current taxonomic treatment. We found that C. fragilis subsp. cavolinii is monophyletic and limited to mountains and hills of central Italy. On the contrary, C. fragilis subsp. fragilis shows a higher genetic variability and a broader distribution in central and southern Italy, with a wider altitudinal range from coasts to mountain cliffs. We confirmed that both subspecies are narrowly calcicolous and have similar ecological requirements, but C. fragilis subsp. cavolinii occurs in colder habitats. Our results forecast a significant distribution contraction in the long term.

Stuccoes are very delicate decorative elements of Roman age. Very few of them survived almost intact to present days and, for this reason, they are of great interest to restorers and conservators. In this study, we combined metabarcoding and untargeted metabolomics to characterise the taxonomic and metabolic profiles of the microorganisms forming biofilms on the stuccoes located on the ceiling of the laconicum, a small thermal environment in the archaeological park of Baia (southern Italy). We found that some samples were dominated by bacteria while others by eukaryotes. Additionally, we observed high heterogeneity in the type and abundance of bacterial taxa, while the eukaryotic communities, except in one sample (at prevalence of fungi), were dominated by green algae. The metabolic profiles were comparable across samples, with lipids, lipid-like molecules and carbohydrates accounting for roughly the 50% of metabolites. In vitro and in vivo tests to remove biofilms on stuccoes using essential oils blends were successful at a 50% dilution for one hour and half. This integrative study advanced our knowledge on taxonomic and metabolic profiles of biofilms on ancient stuccoes and highlighted the potential impacts of these techniques in the field of cultural heritage conservation.

The present study investigated the correlation between the degradation processes of cultural heritage and the environmental parameters of the semi-confined site that houses it. The latter is a semi-underground room (nymphaeum) found in the Archaeological Park of Baia (Italy) dating back to the third century; it is decorated with marine motifs and painted with frescos techniques from the same period. Relative humidity and temperature were hourly registered, and the collected data were used to derive daily and annual profiles. The effects of microclimate induced degradation were investigated employing various techniques, such as Ion Chromatography for the chemical characterisation of deposits, and Thermography, for the individuation of biological layers. The data obtained showed that the underground environment, partially submerged by rising brackish water, was affected by the presence of biodeteriogens, whose distribution and growth is strongly favoured, above all, by the environmental parameters and by the substrate characteristics. All the data were then cross-referenced to obtain a complete knowledge of the conservation frameworks of the environments, essential to identify the most compatible and effective restoration methodologies to be applied in the conservation of the nymphaeum.

This study is aimed to compare, through laboratory experimentations, the efficiency of UV-C irradiation and an essential-oils-based product as tools to reduce the biofilm identified in a semi-hypogeum room located in the archaeological park of Baia, Italy. During this study, the autotrophic component of the original biofilm, mostly composed of Chlorophyceae and Cyanophycean, was isolated in the laboratory, while simultaneously, the composition of the pigments used for the fresco paintings was examined in situ through X-ray fluorescence. These examinations were necessary for the creation of test samples that were similar to the original surfaces and used for subsequent experiments. The plaster testers were contaminated with artificial biofilm, exposed to UV-C at a distance of 80 cm for a fixed time interval and treated with ESSENZIO©, a product based on oregano and thyme essential oils, to eradicate the biological species. The treatment’s effectiveness was then assessed by employing optical microscopy and spectrometric techniques applied to the areas previously occupied by the biofilm on the different test samples. To obtain an additional parameter to evaluate the treatments efficacy, the concentrations of the photosynthetic pigments were also measured by spectrophotometry. Results showed that biofilms were successfully removed by the irradiation of the surfaces and by the essential-oils-based product at a dilution of 50% in demineralized water with a time of application of 1 h and 30 min; in addition, no visible change of the pigments used on the testers were observed, demonstrating the high efficiency of the treatments against biodeteriogens. The two methods and their different mechanisms of action have provided interesting aspects that suggest a combined strategy to contrast and prevent biological growth in archaeological contexts.

Caves represent unique habitats for the development of microbial communities due to particular environmental conditions. Mural paintings occurring in caves suffer from degradation caused by natural processes in which microorganisms are significantly involved. The characterization of the microbial biofilm with non-destructive analysis is important to better preserve and safeguard these artifacts. This study aimed at investigating the microbial communities colonising the frescoes in the Fornelle cave (Calvi Risorta, Caserta, Italy) using a metabarcoding approach. We found a high representation of eubacteria, followed by cyanobacteria, fungi, and microalgae. This study confirmed the potential of non-invasive techniques as DNA metabarcoding as powerful tool for conservation and restoration of artworks.

Caves present unique habitats for the development of microbial communities due to their peculiar environmental conditions. In caves decorated with frescoes, the characterization of microbial biofilm is important to better preserve and safeguard such artworks. This study aims to investigate the microbial communities present in the Fornelle Cave (Calvi Risorta, Caserta, Italy) and their correlation with environmental parameters. The cave walls and the wall paintings have been altered by environmental conditions and microbial activity. We first used light microscopy and scanning electron microscopy (SEM) and X-ray diffraction to characterise the biofilm structure and the mineral composition of substrata, respectively. Then, using both culture-dependent (Sanger sequencing) and culture-independent (automated ribosomal intergenic spacer analysis, ARISA) molecular methods, we demonstrated that the taxonomic composition of biofilms was different across the three substrata analysed and, in some cases, positively correlated with some environmental parameters. We identified 47 taxa in the biofilm samples, specifically 8 bacterial, 18 cyanobacterial, 14 algal and 7 fungal taxa. Fungi showed the highest number of ARISA types on the tuff rock, while autotrophic organisms (cyanobacteria and algae) on the frescoes exposed to light. This study confirms that caves constitute a biodiversity-rich environment for microbial taxa and that, in the presence of wall paintings, taxonomic characterization is particularly important for conservation and restoration purposes.