Search

Parengyodontium album is a fungal species that frequently occurs in the cultural heritage environment. Although three subclades were initially described in the species, no study has sought to determine the occurrence of each subclade in the cultural heritage context. These subclades are easily distinguishable phylogenetically, but their morphological identification is more difficult. Eighteen strains isolated from different cultural sites and initially identified as P. album were studied phylogenetically, morphologically, and in terms of their susceptibility to econazole nitrate 0.2%, an antifungal product used as preservation treatment in cultural heritage domain. The phylogenetic study revealed that all studied strains belonged to P. album subclade 1 or P. torokii (P. album subclade 3) and none belonged to P. album subclade 2. The morphological study revealed the best characteristics to differentiate the three subclades/species, namely, the ability of the strains to grow at 32 C and 35 C on potato dextrose agar (PDA) medium and the shape of conidia. Finally, the strains displayed variable susceptibilities to econazole nitrate, with no apparent link to any particular subclade/species. [ABSTRACT FROM AUTHOR]

Featured Application: The method described in this study consists of the preparation and analysis of mycelium samples for the identification of Serpula lacrymans by FTIR. The dry rot fungus Serpula lacrymans is the most destructive fungal agent of wood building materials in Europe, Russia, North America, and Japan. The identification of this wood-deteriorating agent and the discrimination of different fungal isolates is very important for the control of buildings in general and for the preservation of cultural heritage in particular. The objective of the study was to develop a Fourier transform infrared (FTIR) method coupled with a partial least square discriminant analysis (PLS-DA) for the sample preparation and identification of S. lacrymans. Five distinct S. lacrymans strains were analysed and compared to two strains of unrelated fungal species. Different methods of mycelial growth, sample preparation, and FTIR spectral data normalisation were compared. FTIR analysis of a harvested mycelium grown on the surface of a polyether sulfone microfiltration membrane deposited on a malt extract agar medium, followed by vector normalization and PLS-DA statistical analysis, resulted in 100% correct attribution at phylum, species, and strain level, regardless of the type of standardization used. This study confirms the applicability of FTIR spectroscopy for the identification of S. lacrymans and the discrimination of different strains belonging to this species. [ABSTRACT FROM AUTHOR]

In La Glacière cave (France), the touristic activity has been conducted to an environmental parameter change that has led to photosynthetic organism proliferation (microalgae, diatoms, cyanobacteria, bryophytes). The present study is focused on bryophyte development occurring in the show cave that was responsible of limestone biodeterioration. In order to understand the colonization process of limestone, we have maintained limestone blocks under optimal Lampenflora growth conditions. Moreover, some limestone blocks were painted with several pigments that were used in the prehistory (e.g., red ocher, bone char). Microorganisms and bryophyte growth were monitored during 1 year, and then, the block samples were treated using UV-C light (254 nm). Thus, obtained results were compared with in situ treatment in La Glacière cave. Results have showed dense bryophyte propagation on the several blocks. However, the growth rate was correlated with the chemical composition of the pigment. In fact, the presence of some chemical elements such as As, Cr, Ti, and Co contributed to reduce bryophyte growth. Finally, moss treatment using UV-C light has demonstrated high efficiency under in situ condition, while a fast recolonization has been observed for samples maintained in laboratory. This difference was explained by the high bryophyte density under laboratory conditions that make UV-C light penetration difficult. [ABSTRACT FROM AUTHOR]

Microbial organisms can cause huge crises in decorated caves, as seen in emblematic sites such as Lascaux cave. The preservation of such sites involves understanding the healthy microbial behavior of caves before the damage occurs. Indeed, knowledge of normal cave behavior is a prerequisite to identifying potential imbalance. This study seeks to determine whether models of aerobiological behavior could be identified in several caves of different sizes, ranging from rock shelters to large caves that are open or closed to the public. Aerial rates of fungi and bacteria were monitored over 3 years in nine sites in Dordogne (France). This study revealed that in a context of caves where public visits were carefully managed, fungal and bacterial rates were more affected by the size of the caves than by the opening of sites to the visitors. The study confirmed that large caves can generally be described as "self-purifying caves" as they were strongly affected by the exterior environment at their entry but much less so at locations further inside the cave, while small caves can be described as "non-self-purifying caves" since they were strongly affected by the exterior environment throughout their whole length. The results also highlighted the difficulty to determine a limit value of microbial rates valid for all caves because of the specificities of each one. [ABSTRACT FROM AUTHOR]

Purpose: This study focuses on analysis of the archaeal and fungal diversity associated with gypsum efflorescences damaging the walls of the Sorcerer's prehistoric cave registered as a world cultural heritage site. Method: Archaeal 16S rDNA and fungal internal transcribed spacer (ITS) clone libraries were constructed and analysed. Results: Two thaumarchaeotal OTUs belonging to the Nitrososphaeraceae family dominated the archaeal community (100% of clones). Nitrososphaeraceae are obligate aerobic, chemolithoautotrophic organisms that derive their energy from the oxidation of ammonia and may contribute to primary productivity in the cave. Seven fungal OTUs belonging to Ascomycota and one belonging to Basidiomycota were present. The Cordycipitaceae family, mainly represented by entomophilous fungi, dominated the analysis (66.7% of clones). Conclusion: We show that archaeal and fungal OTUs are associated with gypsum efflorescences damaging the walls of the Sorcerer's cave. The role of these microorganisms in the deterioration of the walls of the cave remains to be determined. [ABSTRACT FROM AUTHOR]

The preservation of decorated caves is a great challenge that has been reinforced by the microbial crisis occurring at emblematic sites such as the Lascaux and Altamira caves. To date, little is known about the microbial behavior of caves. One difficulty is that the term "cave" covers a wide variety of sites and structures. Past studies concentrated on caves with microbial disorders and were generally carried out in a time frame that was too short to gain an adequate picture of healthy microbial behaviors, the sine qua non of detecting potential imbalance. The aim of this study was to determine whether models of aerobiological behavior could be identified in several decorated caves. We monitored aerial rates of fungi and bacteria in five decorated caves of the Gard department (France) for periods of 2 years or more. A model behavior was identified in each cave. These models were cave dependent and were also season dependent in some caves. Following our fungal results, we suggest separating the caves into two groups. The caves which were strongly affected by the external environment throughout their entire length are the "non-self-purifying caves". The caves which were only affected by external environment at the entrance are the "self-purifying caves". [ABSTRACT FROM AUTHOR]

Photosynthetic biofilms proliferating on heritage monuments represent a major threat for curators leading to biodegradation and esthetic issues. Previous studies demonstrated that UV-C, used as a tool for biofilm eradication, is a promising avenue to combat microbial proliferation. In this study, this environmentally friendly method was tested on biofilm-forming Chlorella vulgaris suspension. Algal physiological response to UV-C was then assessed. Results showed that > 10 kJ m−2 UV-C exposure was enough to directly kill cells whereas low UV-C exposure reduced quantum yield of photosystem II and inhibited both respiration and photosynthesis. Clear relationships between UV-C exposure times and physiological responses were found. In addition, the use of VIS-light after UV-C treatment enhances chlorophyll bleaching. Our findings contribute to a better understanding of the physiological responses of Chlorella vulgaris to UV-C radiation allowing thus an optimization of the UV-C treatment reported in our previous studies. [ABSTRACT FROM AUTHOR]

Green microalgae colonizing stone surfaces represent a major problem for the conservation of heritage monuments, since they lead to biodegradation and aesthetic issues. Previous studies in La Glacière show cave (France) have demonstrated that UV-C may have a strong effect on microalgae, thus leading to chlorophyll bleaching, which was increased when biofilms were maintained under VIS-light condition unlike to those maintained in the dark. To understand the physiological mechanisms underlying this response and in order to optimize in situ treatment, 30 kJ m−2 UV-C exposure times were applied to Chlorophyta Chlorella sp. and chlorophyll degradation kinetics were then monitored. UV-C irradiation was enough to inhibit photosynthesis and to directly kill all algal cells. Results also showed that chlorophyll a was degraded faster than chlorophyll b and that 14 h were necessary for complete degradation of all the present chlorophyll. In addition, our results highlighted the importance of visible light exposition after UV-C treatment which leading to chlorophyll bleaching. Irradiated algae cultivated in the dark were still green 5 days after treatment while cultivated samples in the light lost their green color after 14 h. An efficient UV-C treatment applicable to show caves and other heritage monuments was proposed. [ABSTRACT FROM AUTHOR]

Ultra-violet C (UV-C) treatment is commonly used in sterilization processes in industry, laboratories, and hospitals, showing its efficacy against microorganisms such as bacteria, algae, or fungi. In this study, we have eradicated for the first time all proliferating biofilms present in a show cave (the La Glacière Cave, Chaux-lès-Passavant, France). Colorimetric measurements of irradiated biofilms were then monitored for 21 months. To understand the importance of exposition of algae to light just after UV radiation, similar tests were carried out in laboratory conditions. Since UV-C can be deleterious for biofilm support, especially parietal painting, we investigated their effects on prehistoric pigment. Results showed complete eradication of cave biofilms with no algae proliferation observed after 21 months. Moreover, quantum yield results showed a decrease directly after UV-C treatment, indicating inhibition of algae photosynthesis. Furthermore, no changes in pigment color nor in chemical and crystalline properties has been demonstrated. The present findings demonstrate that the UV-C method can be considered environmentally friendly and the best alternative to chemicals. This inexpensive and easily implemented method is advantageous for cave owners and managers. [ABSTRACT FROM AUTHOR]

A laboratory investigation of UV-C effects was conducted over a 62-h period: a much higher dose than in classic UV-C treatment was applied to five pigments and two painting binders used by prehistoric humans. Colorimetric parameters were compared to a control to see if UV-C can change pigment and binder color. Infrared spectroscopy, scanning electron microscopy, inductively coupled plasma and X-ray crystallography were also carried out to confirm colorimetric measurement. In order to understand how microorganism may physically deteriorate paintings, limestone blocks were painted and monitored until their complete colonization by algae, cyanobacteria, fungi and/or mosses. The results show that UV-C has no effect on mineral compounds. Conversely, it is noteworthy that binder color changed under both UV-C light conditions as well as in visible light. Concerning painted blocks, a fast proliferation has been observed with deterioration of the paintings. These results show the high importance of treating biofilm as soon as possible. Moreover, these findings may be a promising avenue inducing cave managers to use friendly UV-C light to treat contaminated cave paintings and also in the prevention of biodeterioration by lampenflora. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biodeterioration can be defined as any undesired change of the properties of a material caused by biological activity of living organisms. The biodeterioration of stone materials is related to the production of pigments (aesthetic action), to cell metabolism (biochemical action) and to the mechanical action of the biomass colonizing the material during its growth (physical action). Quantification of the sessile biomass and characterization of microbial communities colonizing stone are essential first steps to ensure the diagnosis of biodeterioration processes and to implement control strategies and appropriate treatment. Different destructive and non-destructive approaches can be used to sample stone specimens from monuments: scraping, swab using, and cutting. Different analytical methods can be used depending on the type of microorganism sought: determination of chlorophyll content and color analysis for pigmented microorganisms; measurement of in situ physiological activity of surface microcolonies by applying fluorogenic substrate analogues or confocal laser scanning microscopy observations after CTC staining for active biomass; scanning or transmission electron microscopy observation for biofilm visualization; enzyme-linked immunosorbent assay for the investigation of both microorganisms that can and cannot be cultured; classical microbiological methods, which consist in cultivation of microorganisms on synthetic media; and molecular methods for the study of microbial biodiversity based on the polymorphism of molecular markers using PCR, hybridization, classical or high throughput sequencing. The aim of this review is to present basics of the different biodeterioration mechanisms and to focus on the main techniques that can be used to characterize and quantify the biodeterioration biomass. [ABSTRACT FROM AUTHOR]

Biological aerosols from air constitute a significant source of exposure to microorganisms in public places. Airborne microorganisms are involved in the development of certain respiratory symptoms, allergies, or infections among users and occupants. Various sampling instruments have commonly been used in aerobiology to collect bacteria and fungi suspended in the air. The objective of this study was to develop a reliable procedure for sampling in indoor public environments presenting different levels of occupancy, airborne bacteria and fungi to be subjected to molecular analysis (bacteria and fungi quantitative PCR, capillary electrophoresis single strand conformation polymorphism fingerprinting). Four different sampling devices were tested in situ in an office building (open-plan type) and the sampling strategy chosen was tested in two museum contexts. In accordance with the drawbacks involved to our study (quantitative and qualitative aspects, cost, and overcrowding), cyclone device appeared to be most suitable. The results underline the effectiveness of this high-volume aerosol sampling device for both qualitative and quantitative molecular analysis. Four in situ sampling collections were carried out in 1 day in the Louvre Museum to study quantitative and qualitative variations of airborne bacterial and fungal diversity. The quantitative results revealed a similar order of magnitude for the numbers of both bacteria and fungi. In the Louvre Museum, the samples yielded between 3.7 × 104 and 4.1 × 104 genome equivalent (GE) bacteria/m3 air and between 5.0 × 104 and 5.9 × 104 GE fungi/m3 air and in the Decorative Arts Museum between, 2.1 × 104 and 2.5 × 104 GE bacteria/m3 air and between 1.4 × 104 and 1.7 × 104 GE fungi/m3 air. The results also indicate that the dominant bacterial community displayed a stable structure over a short period of time whereas dominant eukaryotic airborne community appeared more variable. [ABSTRACT FROM AUTHOR]

A major fungal invasion was discovered in the prehistoric painted cave of Lascaux in France in Sep 2001. At least three species of the Fusarium solani complex were isolated and identified with a portion of the translation elongation factor 1α gene (EF-1α), a portion of the nuclear large subunit rDNA (LSU) and nuclear ribosomal intergenic spacer region (ITS). This study represents the first time that Fusarium species have been reported from a cave containing prehistoric paintings. Significant interspecific molecular variability was observed, suggesting that there might have been repeated introduction of the species, possibly carried by water from soils above the cave. [ABSTRACT FROM AUTHOR]