Search Results (107)

Ornamental fountains in the Alhambra and Generalife (Granada, Spain) constitute complex socio-ecological systems where water, stone, and biological communities interact, making them highly vulnerable to biodeterioration caused by phototrophic microorganisms such as cyanobacteria, green algae, and diatoms. Conventional chemical biocides, although widely applied, present significant drawbacks including toxicity, material degradation, ecological imbalance, and limited long-term effectiveness. In this context, this study evaluated the potential of algicidal bacteria as a sustainable alternative for controlling phototrophic growth in heritage environments. Water samples from eight ornamental fountains were analyzed using 16S ribosomal RNA (16S rRNA) gene sequencing to characterize bacterial communities and identify taxa previously reported with algicidal activity. Statistical analyses were conducted to assess relationships between microbial community structure and biofilm development. In parallel, functional screening assays using filtered fountain waters against Chlorella vulgaris were performed to evaluate intrinsic inhibitory capacity. The most active sample was selected for bacterial isolation and further validation through co-culture assays, cell density measurements, and pulse-amplitude-modulated (PAM) fluorometry. A total of 18 genera with reported algicidal capacity were detected, representing a substantial fraction of the microbiome across all samples. However, no significant association was found between these taxonomic metrics and biofilm development, highlighting a decoupling between taxonomic composition and functional activity. The most active isolate, identified as Stenotrophomonas maltophilia strain LIG25, caused a rapid decline in photosynthetic efficiency and achieved more than 98% inhibition of algal growth. These findings demonstrate that ornamental fountain microbiomes represent a reservoir of native biocontrol agents and support the development of eco-friendly strategies for cultural heritage conservation. Full article

Synthetic polymers are widely used in stone conservation, yet their long-term biological stability remains insufficiently evaluated. This study investigates the microbial susceptibility of three commonly used acrylic consolidants, Paraloid B-72, B-66, and B-44, applied to deteriorated limestone. Bacteria, fungi, and actinomycetes were isolated from a deteriorated limestone false door and screened for acid production. From each microbial group, only the strong acid-producing isolates were selected for further investigation, including evaluation of their ability to utilize the three Paraloid resins as sole carbon sources and their deterioration potential on limestone cubes before and after consolidation. Deterioration was assessed by weight loss, compressive strength testing, stereomicroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). All selected strong acid-producing isolates demonstrated the ability to grow on the tested polymers, confirming their biodegradation potential. Mixed microbial cultures caused greater weight loss and compressive strength reduction than single isolates, attributed to synergistic metabolic interactions. Among the consolidants, Paraloid B-72 showed the highest susceptibility to microbial attack, while Paraloid B-66 exhibited comparatively greater resistance, attributed to the steric hindrance of its isobutyl side groups and higher surface hydrophobicity. FTIR and XRD analyses confirmed ester bond hydrolysis, progressive gypsum formation, and structural alteration of the limestone substrate. These findings demonstrate that acrylic consolidants commonly used in stone conservation are not biologically inert and may actively contribute to biodeterioration under microbial colonization, highlighting the need for developing bio-resistant conservation materials. Full article

Dajue Temple, a representative ancient architectural heritage in North China, houses numerous lacquered wooden components of exceptional historical and artistic value. Prolonged environmental exposure causes severe dark discoloration and black spotting on lacquer surfaces, threatening their structural integrity. This first investigation into the damage identifies the spots as microbial in origin, with Cladosporium spp. as the primary agent driving deterioration and possessing wood-degrading capabilities. Antifungal tests show that thymol, clove essential oil, and nano-silver gel are all effective inhibitors. We proposed targeted, relic-friendly microbial control strategies tailored for ancient lacquered wooden components. These findings provided scientific guidance for the sustainable conservation and restoration of lacquered architectural elements in historic temples and comparable cultural heritage sites. In future work, environmental monitoring and the biocides’ compatibility should be involved, which will help to clarify microbe–environment interactions, enable early warning of biodeterioration risks and explore the wood-friendly biocides. Full article

Stone heritage deteriorates through physical, chemical, and biological processes driven by water, climate, and microbial colonization. Multifunctional polymeric coatings combining hydrophobic and antimicrobial moieties have emerged as a promising conservation strategy, yet a substantial gap remains between laboratory innovation and real-world performance. This review critically examines advances from 2021 to 2026, covering wetting theory, antimicrobial mechanisms, and material architectures, including molecularly integrated systems, Sol–Gel hybrids, nanocomposites, and layered systems. Long-term studies on the Aurelian Walls in Rome and stone in Reims show that biocidal efficacy typically declines within one to two years despite the chemical persistence of the coatings. In parallel, hydrophobic performance often deteriorates over time due to UV exposure, particulate deposition, and surface chemical changes, leading to increased wettability and reduced protective efficiency. Substrate porosity governs durability and visual compatibility (ΔE* < 5 threshold), while treatments can reshape microbial communities, favoring stress-tolerant meristematic fungi. Regulatory pressure on fluorinated compounds drives the development of more sustainable alternatives. Emerging directions include stimuli-responsive systems, self-healing materials, slippery interfaces, and precision polymer architectures. However, future progress will depend on tailoring formulations to major lithotypes, improving compatibility with porous substrates, and validating performance through standardized accelerated aging and multi-year field trials. Bridging laboratory design with environmental exposure data and conservation practice will be essential for achieving durable and culturally acceptable protection strategies. Full article

Microorganisms such as Arthrobacter spp. are important agents of biodeterioration in cultural heritage (CH) environments, causing orange–yellow chromatic alterations and contributing to substrate degradation. This study evaluates two complementary tools for the rapid detection and mitigation of Arthrobacter spp.: a newly designed genus-specific RNA–fluorescence in situ hybridisation (FISH) probe (Art1420-Cy3) and an antimicrobial peptide fraction produced by Saccharomyces cerevisiae ISA 1028. The RNA-FISH probe Art1420-Cy3 showed high specificity and sensitivity, labelling 80–85% of Arthrobacter cells at 10% (v/v) formamide and enabling their detection by epifluorescence microscopy and flow cytometry. The peptide fraction exhibited pronounced bactericidal activity, reducing Arthrobacter culturability from ~10⁸ to ~10¹ CFU/mL within 48 h, while also inhibiting other biodeteriogenic microorganisms. Overall, these findings outline the basis for an integrated and CH-compatible approach that combines precise Arthrobacter cells detection and identification with targeted, biologically derived control. Although further validation using real heritage samples and application protocols specifically tailored to sensitive materials is required, this strategy shows strong potential as a sustainable alternative to conventional chemical biocides and as a practical framework for detecting and mitigating pigment-producing biodeteriogens in CH and other vulnerable environments. Full article

Filamentous fungi are among the most significant biological agents responsible for the biodeterioration of organic cultural heritage materials preserved in archives, libraries, and museums. Cellulose-based substrates—such as paper, papyri, and plant-derived textiles—as well as protein-based materials, including parchment and leather, provide favourable conditions for fungal colonization due to their chemical composition and hygroscopic behaviour. Once activated, fungi contribute to deterioration through a combination of mechanical penetration and biochemical processes, including the secretion of hydrolytic enzymes, organic acids, and pigmented metabolites, which progressively compromise the structural integrity and visual appearance of heritage objects. This review aims to critically synthesize current knowledge on the mechanisms of fungal biodeterioration affecting organic heritage materials, with particular attention to material-specific vulnerabilities, indoor environmental drivers, and implications for preventive conservation. Recent advances in fungal ecology have highlighted the presence of xerophilic and extremotolerant taxa capable of persisting under conditions traditionally considered unfavourable for microbial growth, posing new challenges for conservation management. Rather than attributing biodeterioration directly to global climate change, this review explicitly emphasizes the role of indirect and building-mediated climate-related stressors—such as increased frequency of moisture intrusion events, infrastructure vulnerability, and microclimatic instability within buildings—in shaping fungal risk in indoor heritage environments. The integration of environmental monitoring, microbiological diagnostics, and predictive risk-assessment tools emerges as a key strategy for early detection and mitigation. By consolidating interdisciplinary evidence from microbiology, materials science, and heritage conservation, this work underscores the need to shift from reactive restoration toward anticipatory, risk-based preventive approaches to ensure the long-term preservation of organic cultural heritage materials. Full article

The presence of lithobionts has historically been associated with biodeterioration, posing significant challenges to the conservation of culturally and historically significant stone heritage. This perception stems from abundant evidence of their role in biogeophysical processes, such as mechanical disruption of stone structures, and biogeochemical processes, which chemically alter stone composition through metabolic activity. These processes, while integral to natural systems, often accelerate the weathering and deterioration of heritage materials. Coupled with the aesthetic impact of lithobiont growth, frequently resulting in discoloration or obscuring of intricate details, such effects have justified the widespread removal of these organisms from heritage surfaces. However, recent research has revealed a far more nuanced picture. These communities can enhance biodiversity, contribute to the perceived authenticity of aged monuments, and, in some cases, form a biological layer that shields stone from pollutants and weathering forces. Moreover, developments in biomediated conservation approaches, such as biocementation and biocleaning, highlight their potential as sustainable allies in preservation. This dual role of lithobionts—both as friends and foes in preservation—is central to this review. This review focuses on how these organisms—with a particular emphasis on fungi, often perceived as enemies of conservation—may also serve as unexpected partners in safeguarding our stone heritage, emphasizing the need for case-by-case evaluation of active communities and their environmental context. Full article

Ancient books and documents constitute an important cultural heritage, which are composed by different supports, such as cardboard, parchment and paper. Due to their composition (animal- and plant-based matrices), they allow bacteria and fungi to thrive, causing the phenomenon of biodeterioration, an ecological succession in parchment. Four ancient books called “Compositionum” from the Apostolic Vatican Archive, made of the same materials, exposed to weather-beating conditions and showing different degrees of deterioration, were analysed by a multidisciplinary approach: DNA metabarcoding using NGS, Light Transmission Analysis and Raman and FTIR spectroscopy. The results highlighted how the biodeteriogen community composition changed from the least to the most damaged, without evidence of significant microbial transfer across the three matrices. The results allow confirmation of the ecological succession as biodeterioration process, including cardboard and paper, in addition to in parchment. These results give important insight for the conservation and restoration practices of all matrices. Full article

Stone relics exposed to outdoor environments frequently experience surface deterioration, with red stains being a common and persistent issue. The stains often observed on marble and limestone surfaces arise from complex interactions involving chemical reaction, pollutant deposition, and microbiological process. Although microbial colonization has been associated with biodeterioration, the specific mechanisms remain poorly understood. This study focuses on the red stains found on the Danbi marble carvings at Beijing Confucian Temple and the Imperial College. Combining microbial cultivation, molecular identification (ITS sequencing), SEM-EDS (Scanning Electron Microscopy), Raman spectroscopy, and HPLC-MS (high-performance liquid chromatography with mass spectrometry), we identified the pigment-producing fungus Lizonia empirigonia as the dominant agent, with no evidence of inorganic contributors such as iron/lead oxides. Metabolite profiling revealed flavonoids and polyketides as key coloring material, while controlled infection experiments demonstrated the fungus’s reliance on exogenous organic matter rather than direct stone degradation. Our findings highlight microbial activity as a primary driver of red stains in marble relics and underscore the importance of organic contaminant control in conservation. Full article

The growth of microalgae poses a significant threat to the preservation of stone heritage, particularly in ornamental fountains and water-related architecture. Traditional chemical cleaning methods, such as quaternary ammonium compounds and chlorine-based solutions, are often ineffective and can be harmful to both the environment and cultural properties. In response, biocleaning, which involves the use of live microorganisms and is part of biorestoration, is gaining prominence in cultural heritage conservation, offering a sustainable alternative to conventional methods. The use of microorganisms antagonistic to microalgae growth has been extensively studied in environmental biotechnology to eliminate harmful algae, though its application in heritage conservation remains limited. This review summarizes current knowledge on bacteria capable of inhibiting microalgae growth, discussing their mechanisms, effectiveness, and potential applications, alongside the environmental and economic benefits and challenges of these methods. By collating and critically assessing available information, this paper aims to serve as a comprehensive resource for conservators, restorers, and researchers interested in innovative and sustainable approaches to combat biodeterioration in stone heritage, thereby fostering the development of effective and environmentally sustainable treatments for such culturally significant properties. Full article

Various heritage objects can be subjected to various types of biodegradation and biodeterioration. Mold fungi can destroy many types of art—be it monumental art or easel paintings. Tempera paintings on wood are at risk of biodeterioration, since the wide variety of organic and inorganic materials in art objects often provide an optimal habitat for biological colonization, causing aesthetic and structural damage. In this regard, timely identification and characterization of their microbiological destructive potential are critical. The fungi Syncephalastrum sp. STG-160 and Cladosporium sphaerospermum STG-161, isolated from bio-lesion sites of the 16th century icon “Descent into Hell” from State Tretyakov Gallery, Moscow, were identified and characterized morphologically and molecularly in our work. Syncephalastrum sp. was found in an unusual habitat that has not been previously described for this species. To determine the biodegradability of the identified fungi, their cells were inoculated onto mock layers—egg yolk ochre, cobalt green tempera pigments, and watercolor black. The results show that some pigments were more degradable than others. The addition of cobalt green completely inhibited STG-161 growth and significantly deceleratedSTG-160 mycelium development, most likely due to the presence of heavy metal ions in the pigment. Ochre, a frequently used pigment in restoration practice, is the most degradable material for Syncephalastrum sp. STG-160. Combining culture-dependent methods with SEM and fluorescence microscopy allowed us to identify an invisible individual spore of Syncephalastrum sp. STG-160 and a single hypha of Cladosporium sphaerospermum STG-161 directly on the icon’s surface in clean-contaminated zones, potentially allowing their development in cases of adverse temperature and humidity conditions. Therefore, in order to ensure rapid and effective conservation, it is crucial to assess and quantify the presence of biological systems causing damage to the heritage object itself as well as its individual art components. Full article

George Town, the capital of Penang, Malaysia, was inscribed as a UNESCO World Heritage Site in 2008 and is renowned for its multicultural architectural surfaces. However, these historic façades face significant deterioration challenges, particularly biodeterioration caused by weed growth on wall surfaces under hot and humid equatorial conditions. Root penetration is a critical surface defect, accelerating mortar decay and threatening structural integrity. To address this issue, this study proposes YOLOv11-SWDS (Surface Weed Detection System), a lightweight and interpretable deep learning framework tailored for surface defect detection in the form of weed intrusion on heritage buildings. The backbone network was redesigned to enhance the extraction of fine-grained features from visually cluttered surfaces, while attention modules improved discrimination between weed patterns and complex textures such as shadows, stains, and decorative reliefs. For practical deployment, the model was optimized through quantization and knowledge distillation, significantly reducing computational cost while preserving detection accuracy. Experimental results show that YOLOv11-SWDS achieved an F1 score of 86.0% and a mAP@50 of 89.7%, surpassing baseline models while maintaining inference latency below 200 ms on edge devices. These findings demonstrate the potential of deep learning-based non-destructive detection for monitoring surface defects in heritage conservation, offering both a reliable tool for sustaining George Town’s cultural assets and a transferable solution for other UNESCO heritage sites. Full article

Biodeterioration represents a major threat to cultural heritage, as microbial colonization can cause both esthetic and structural damage. The use of conventional chemical biocides raises concerns due to environmental and health risks, potential substrate deterioration, and the emergence of resistant strains. In this study, an ozone-loaded bacterial cellulose (OBC) hydrogel was investigated as an eco-friendly, broad-spectrum antimicrobial treatment in the case study of the Cryptoporticus of the Baths of Trajan (Rome, Italy), a hypogean archeological site where some structures are severely affected by phototrophic biofilms. Microorganisms isolated from a colonized wall were employed in laboratory assays. OBC hydrogel exhibited strong antimicrobial activity, with >90% bacterial mortality within 10 min, complete inhibition of fungal spore germination after 24 h, and a marked reduction in microalgal chlorophyll fluorescence comparable to heat-killed controls. Furthermore, tests on Carrara marble and brick specimens artificially contaminated with microalgae confirmed the removal of green staining, restoring surface chromatic parameters (ΔE* < 5) comparable to those obtained with a commercial biocide. In situ applications demonstrated significant suppression of green biofilm for at least two months. These findings support OBC hydrogel as a sustainable, effective, and non-toxic alternative to conventional biocides for controlling microbial and microalgal colonization on cultural heritage surfaces. Full article

The nymphaeum originated as a monument dedicated to the nymphs and defined as a natural cave with a water source. Over time, it has been transformed into an artificial cave with the presence of fountains, statues and wall paintings. The nymphaeum is exposed to specific environmental conditions, leading to biodeterioration caused by vegetal organisms that find an ideal environment for their growth. This study aimed to document the vegetation present inside and outside the Carolei’s Nymphaeum, as well as the biofilm on the interior walls, particularly the painted walls. The biological work is part of a large-scale project involving building materials, thermo-hygrometric parameters, and partial pilot restoration work. Multiple approaches were used for biological analysis by combining microscopic, culture, and molecular techniques. We identified Pteridophytes, Angiosperms, and mosses, as well as fungal taxa, cyanobacteria, and chlorophytes in the biofilms. The results indicate that there is a very heterogeneous organism composition with significant biodeterioration potential. Biodeterioration is one of the major problems in the prevention, conservation, and restoration of cultural heritage, and the data gathered in this research may help to enhance the understanding of issues and develop suitable strategies for restoration, upkeep, and accessibility and usability. Full article

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. Full article