Biodeterioration Processes Research Articles

Defects induced by gamma irradiation in historical pigments

Abstract The paper presents our results concerning a complex investigation by reflectance spectroscopy (RS) and Electron Paramagnetic Resonance (EPR) of the defects induced by gamma irradiation in 22 different historical pigments. Gamma irradiation is used to destroy microflora and insects which are involved in biodeterioration processes of art works such as paintings. At the same time, it can induce defects i.e. color centers which are likely to modify the original painting colors by altering the embedded pigments. Accordingly, RS was used to quantify, by means of CIELAB color space, the contribution of irradiation defects to the pigments color changes, while EPR spectroscopy, in view of paramagnetic properties of color centers, was used to confirm their presence after irradiation. Our investigations showed that, excepting marble dust whose color alteration was still observable after 3 months, color changes induced by irradiation in all other pigments disappeared after about 30–40 days. In addition, RS as well as EPR measurements suggest that color changes are related to irradiation color centers, this finding being confirmed by the coincidence, within experimental uncertainties, of the half-life time color changes as obtained by these methods.

Adobe wall biodeterioration by the Centris muralis Burmeister bee (Insecta: Hymenoptera: Apidae) in a valuable colonial site, the Capayán ruins (La Rioja, Argentina)

Historic earthen buildings in central western Argentina constitute a valuable resource for studies of recent material culture. Without adequate care and maintenance, these types of buildings are susceptible to damage by physical or biological processes. A specific type of damage was identified in earthen walls of the Capayán ruins, in La Rioja, Argentina. The aim of the present study was to determine the cause of this damage and understand the biodeterioration process. The wall selected for this study exhibited massive erosion in zones used by bees for nesting. These zones presented easily distinguishable patches of coarse appearance on the wall surface. A high density of cavities as a result of the removal of the cells (708 cavities m −2, SD < 5%) was observed. The causal agent was identified as the bee Centris muralis Burmeister. The weight of the material lost from the wall due to biodeterioration was estimated at 729 kg of earth. Erosion in the attacked parts reduced the thickness of the adobe wall ca. 7 cm compared to parts without nests. This study demonstrates that earthen walls are subject not only to damage by weathering, but also to biodeterioration.

Characterizing the Microbial Colonization of a Dolostone Quarry: Implications for Stone Biodeterioration and Response to Biocide Treatments

This study examines the microbial colonization of three fronts of an abandoned dolostone quarry (Redueña, Madrid, Spain) exposed to atmospheric conditions for different time periods since Roman times to the present. Through scanning electron microscopy in backscattered electron mode (SEM-BSE), endolithic colonization was predominantly detected in the most recently exposed front, while in the longer exposed quarry fronts, epilithic forms of growth were most often observed. These observations were confirmed by denaturing gradient gel electrophoresis (DGGE) analysis. Based on the distribution pattern of microbial colonization in the different quarry fronts, we then established a sequence of colonization events that took place over this long time frame. Bioalteration processes related to this sequential colonization were also identified. Characterizing these sequential processes can be useful for interpreting biodeterioration processes in historic dolostone monuments, especially those affecting constructions in the area of the Redueña stone quarry. In a second experimental stage, different biocide treatments were tested on this quarry rock to find the best way to avoid the microbial colonization effects identified. Through combined SEM-BSE/DGGE analysis, the efficacy of several biocides against the microorganisms inhabiting the dolostones was assessed after 4 and 16 months treatment. In general, all treatments were effective at reducing around 80% of the lichen cover, although effects on endolithic lithobiontic communities were dependent on how well the rock surface had been mechanically cleaned prior to treatment and gradually disappeared over time.

The microbial community dwelling on a biodeteriorated 16th century painting

The microbial community dwelling on the damaged parts of a 16th century painting displayed in the medieval church of San Giacomo Maggiore (Bologna-Italy), was evaluated through both culture-dependent and molecular methods. Among the fungal and bacterial isolates, strains belonging to Penicillium and Bacillus genera, respectively, were present. Growth on a standard restoring organic glue paste was assessed for both genera, while degradation of lignocellulosic materials was only ascribed to the fungal fraction of the microbial consortium. Through 16S rRNA gene library screening and Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis, a description of the actual bacterial diversity developed upon the biodeterioration process was obtained. This analysis revealed, along with the isolated bacilli, the presence of a complex community, which also included several heterotrophic bacterial genera. According to this study, the observed biodeterioration phenomenon was due to the biodegradability of the lining materials with the occurrence of environmental conditions that caused the switch from a dormant to a metabolically active state of the heterotrophic consortium.

A review of biological deterioration of library materials and possible control strategies in the tropics

PurposeThe purpose of this paper is to review the current state of research on the various biological agents that could cause deterioration of paper materials and possible intervention strategies against these biotic agents in the tropics.Design/methodology/approachRecent literature in the tropics is reviewed to gain insight into the problems that confront libraries in the tropics as regards the biological deterioration of library materials.FindingsThe paper identifies moulds as the most important biodeteriorating agents of library materials. In addition to destroying, disfiguring and staining books, the moulds have been linked to numerous adverse human health effects that fall into three categories: allergic, toxic and infectious. The other biological agents include bacteria, insects and rodents. The important insects in tropical environment are cockroaches and termites. The warm humid tropical conditions and dirty environment trigger/promote biodeterioration processes and make book deterioration to be more pronounced in the tropics than in the temperate regions.Research limitations/implicationsPhysical visits to the libraries were not carried out and the conclusions reached were based on evidence from scientific literature on the subject in the tropics.Practical implicationsA very useful source of information on how to curb the menace of biological agents against the destruction of library materials in the tropics. These include training programmes for library staff on conservation and preservation of library collections, the creation of awareness on the issue among library users, the adoption of good house keeping practices and modification of storage environment to make them unsuitable for the biodeteriogens. It is recommended that libraries and archives in tropical countries should have preservation guidelines and integrated pest management teams and should also cooperate with scientists in relevant disciplines to be able to find lasting solutions to the problem of biodeterioration of library materials.Originality/valueThis paper looks into the neglected area of biological deterioration of papers which is the main information carrier in libraries. It provides very useful and practical suggestions that libraries in the tropics could adopt to tackle the menace of biological agents.

Role of fungi in biodeterioration process of stone in historic buildings

Fungal ability in production of pigments and organic acids have crucial role in discoloration and degradation of different types of stone in cultural heritage objects. Additionally, stone objects may support novel communities of microorganisms that are active in biodeterioration process. This investigation focuses on mycological analyses of microbial biofilm from two important buildings, made of granite and sandstone, and which were heavily colonized by fungi. The 23 fungal taxa including filamentous microfungi and yeasts with specific distribution on sandstone and granite substrate were isolated. Melanized fungi from Dematiaceae (Deuteromycotina) were dominant. The identified microfungi cause discoloration, as well as mechanical exfoliation of building stone material that was analyzed through mechanical hyphae penetration and production of dark pigments and organic acids.

Documentation of soiled and biodeteriorated facades: A case study on the Coliseum, Rome, using hyperspectral imaging fluorescence lidars

Abstract Non-invasive documentation of historic facades with fluorescence lidar techniques can provide helpful information for the cultural heritage sector, especially when large areas outdoors are to be examined. This paper presents a case study of the Coliseum, Rome, where both cleaned and heavily soiled areas of the monument were scanned and analysed with two fluorescence lidar systems. Biodeterioration processes were also addressed during the experiment, with the aim of assessing the colonisation extent on selected areas of the monument. Results show the usefulness of a mobile fluorescence lidar system for documentation and survey of large surfaces with complex conditions without limiting the public access to the monument.

Isolation of five Rubrobacter strains from biodeteriorated monuments

In the last few years, the microbial colonisation of mural paintings in ancient monuments has been attracting the attention of microbiologists and conservators. The genus Rubrobacter is commonly found in biodeteriorated monuments, where it has been reported to cause rosy discolouration. However, to date, only three species of this genus have been isolated, all from thermophilic environments. In this paper, we studied three monuments: the Servilia and Postumio tombs in the Roman Necropolis of Carmona (Spain), and Vilar de Frades church (Portugal), in search of Rubrobacter strains. In all cases, biodeterioration and the formation of efflorescences were observed, and five Rubrobacter strains were isolated. These isolates showed different physiology and migration in denaturing gradient gel electrophoresis, suggesting they might represent new species within this genus. The isolates reproduced some biodeterioration processes in the laboratory and revealed their biomediation in crystal formation.

Reproducing stone monument photosynthetic-based colonization under laboratory conditions

In order to understand the biodeterioration process occurring on stone monuments, we analyzed the microbial communities involved in these processes and studied their ability to colonize stones under controlled laboratory experiments. In this study, a natural green biofilm from a limestone monument was cultivated, inoculated on stone probes of the same lithotype and incubated in a laboratory chamber. This incubation system, which exposes stone samples to intermittently sprinkling water, allowed the development of photosynthetic biofilms similar to those occurring on stone monuments. Denaturing gradient gel electrophoresis (DGGE) analysis was used to evaluate the major microbial components of the laboratory biofilms. Cyanobacteria, green microalgae, bacteria and fungi were identified by DNA-based molecular analysis targeting the 16S and 18S ribosomal RNA genes. The natural green biofilm was mainly composed by the Chlorophyta Chlorella, Stichococcus, and Trebouxia, and by Cyanobacteria belonging to the genera Leptolyngbya and Pleurocapsa. A number of bacteria belonging to Alphaproteobacteria, Bacteroidetes and Verrucomicrobia were identified, as well as fungi from the Ascomycota. The laboratory colonization experiment on stone probes showed a colonization pattern similar to that occurring on stone monuments. The methodology described in this paper allowed to reproduce a colonization equivalent to the natural biodeteriorating process.

Micro-Raman spectroscopic investigation of external wall paintings from St. Dumitru’s Church, Suceava, Romania

The external sixteenth century wall paintings of St. Dumitru's Church in Suceava (Romania) are suffering visually from deterioration. Fragments of these paintings spallated from the external wall have been studied by micro-Raman microscopy in order to elucidate possible causes of this process. Calcite and alpha-quartz are the components of the substratum indicating that the artists used the Roman fresco technique comprising a limewash putty. No organic binders have been detected in the substrate or pigment application. Amorphous carbon and goethite, alpha-FeOOH, have been identified in areas containing residues of grey and yellow pigments, respectively. Small amounts of gypsum have been detected in the grey areas which we attribute to special attention being given to surface preparation and pigment application in these areas. An abundance of sodium nitrate, nitratine, microcrystals have been observed on the surfaces of many fragments which suggests that a biodeterioration process originating from guano deposits could have been operating in these frescoes.

Microfungal biodeterioration of historic paper: Preliminary FTIR and microbiological analyses

Paper is subjected to numerous biodeterioration processes, which may cause the irreversible degradation of important documents and works of art. Many chemical and physical factors can affect these processes and their behaviour, and fungi seem to play a key role in biodeteriorating paper materials. This study is mainly aimed at verifying the presence of fungi in biodeteriorated 18th century etchings, and characterizing the paper surface by means of Fourier transform infrared (FTIR) spectroscopy and fluorescence under UV radiation. The laboratory tests highlight the presence of fungal entities from all the samples investigated. Specifically, 14 species were identified; three of them were never isolated from paper until now. Furthermore, the data gathered do not confirm the theory according to which there is a correspondence between fluorescence of the stains under UV radiation and the vitality of microfungi. Finally, possible correlations among paper composition (as determined by FTIR), mode of conservation and fungal attack are presented and discussed.

Ecological analysis and biodeterioration processes over time at the Hieroglyphic Stairway in the Copàn (Honduras) archaeological site

The Copàn Hieroglyphic Stairway, one of the most important monuments of the Mayan culture, was excavated at the end of the 1800s. After a few decades it was extensively attacked by mosses and lichens. Different biocide treatments were applied in the late 1970s, and consolidation and stabilization works were carried out in the 1980s and 90s; a tarp was installed in 1985 over the Stairway for protection from rain. The present investigation shows an almost total death of lichens and a heavy reduction of the biodeterioration phenomena on the stone surfaces of this monument. The most frequent species presently growing are cyanobacteria and a few green algae. Notwithstanding this relatively low level of superficial colonization, cross-section staining and SEM analyses at times revealed a heavy biological growth just below the surface. The main structures found were exo-polymeric substances, fungal hyphae and moss protonema. Through a comparative analysis of the biodeteriorative phenomena of other monuments at the site, and with historical records, the relationships between the main ecological factors (water and light) and the biological colonization at the Copàn archaeological site are described. The ecological analysis and the changes that seem to have occurred in the biodeterioration of the Stairway provide useful information for planning future conservative interventions.

Biodeterioration of the Lions Fountain at the Alhambra Palace, Granada (Spain)

Stone works of art exposed to the environment are liable to be deteriorated by the action of biological agents such as bacteria, fungi, mosses, etc. In ornamental fountains, the microorganisms present in water can contribute to these biodeterioration processes. This paper assesses the biodeterioration experienced by the Lions Fountain at the Alhambra Palace in Granada (Spain). Analyses have been made of the biodeterioration of Lions 4, 5 and 9, the biofouling of the fountain basin, and the water supply system. Conventional and molecular biology techniques have identified microorganisms belonging to various microbial groups ( α-, β- and γ- Protebacteria, Chlamydiae/Verrucomicrobia and Eukaryota). Additionally, on the mortar in the sculptures the presence of algae and bryophytes has been observed. X-ray diffraction allowed both the detection of neoformation mineral products that can be related with the presence of microorganisms and the corrosion products in the Lions Fountain. A number of recommendations are made regarding the prevention and control of biodeterioration in this important work of art.

Contributions of in situ microscopy to the current understanding of stone biodeterioration.

In situ microscopy consists of simultaneously applying several microscopy techniques without separating the biological component from its habitat. Over the past few years, this strategy has allowed characterization of the biofilms involved in biodeterioration processes affecting stone monuments and has revealed the biogeophysical and biogeochemical impact of the microbiota present. In addition, through in situ microscopy diagnosis, appropriate treatments can be designed to resolve the problems related to microbial colonization of stone monuments.

The importance of atmospheric effects on biodeterioration of cultural heritage constructional materials

The three important factors influencing the deterioration of monuments and buildings belonging to the cultural heritage are: (a) biodeterioration processes, (b) atmospheric deterioration or weathering of the materials exposed to open air, and (c) natural and anthropogenic pollution. Thus, the environment plays a decisive role in the type and extent of deterioration processes experienced by the cultural property. In the literature on atmospheric corrosion or weathering of structural materials of cultural heritage there is a lack of understanding of the relevance of biodeterioration processes. Moreover, the close relationship between the environment and the microbial communities colonizing monuments and buildings is generally ignored. With the aim of clarifying this relationship a brief overview of several cases of biodeterioration in four sites of Latin American cultural heritage is presented here. An analysis of the structural material composition and its physicochemical characteristics was made in each case by using surface analysis techniques complemented by electron microscopy. Microbiological techniques for the isolation and culture of microbial contaminants were also used, and the information was correlated with experimental data on the concentration of atmospheric pollutants in each particular case. A synergistic relationship between biological and atmospheric effects on the deterioration of structural materials was observed, although in marine and in industrial/urban atmospheres the weathering effects were predominant.

In situ microscopical diagnosis of biodeterioration processes at the convent of Santa Cruz la Real, Segovia, Spain

Abstract This report describes the in situ evaluation of biodeterioration processes occurring in the stone (granodiorite and carbonate) of the Convento de Santa Cruz la Real, Segovia, Spain. Scanning electron microscopy with back-scattered electron imaging (SEM–BSE) and X-ray microanalysis were used to examine stone samples from the convent. Free-living algae and fungi, lichen thalli, mosses, cyanobacteria and bacterial colonies were observed. Some of these organisms were located epilithically, while others were found to inhabit fissures or cavities inside the lithic substrate, a few of which showed an euendolithic ecological niche. Biogeomechanical and biogeochemical processes associated with the presence and action of lithobiontic microorganisms were detected, as well as evidence for the biomobilization of elements by epilithic and endolithic microorganisms. The relative contribution of each lithobiont to these biodeterioration processes were found to vary according to the type of stone and its position in the monument.

Biodeterioration of textiles

Abstract Textiles, particularly those composed of natural organic fibres such as cotton, linen, wool, etc., are readily attacked by microorganisms. Most synthetic fabrics are not readily subject to extensive biodeterioration, but some processing and finishing agents are susceptible to microbial spoilage. Microorganisms can affect all stages of textile processing and storage, with fungi being the most important microorganisms in textile biodeterioration processes. Microbial growth on a textile causes loss of strength and elongation, discolouration and changes in appearance. They follow changes in oxidation state, degree of polymerization and breakdown of molecular structure. There are two main ways of textile protection—control of the environmental physical conditions and treatments with biocides.

In situ evaluation of the biodeteriorating action of microorganisms and the effects of biocides on carbonate rock of the Jeronimos Monastery (Lisbon)

The biodeterioration effects of microorganisms colonizing the cloister terrace wall of the Jeronimos Monastery (Lisbon) were evaluated using several microscopy techniques that allow the in situ examination of lithobiontic communities. The techniques applied were: scanning electron microscopy with back-scattered electron imaging (SEM-BSE), low temperature scanning electron microscopy (LTSEM), transmission electron microscopy (TEM) and an X-ray energy dispersive spectroscopy (EDS) microanalytical system. The stone was seen to be colonized by different lichens and microorganisms and lichen thalli of Thyrea, Aspicilia, Verrucaria and Caloplaca were identified. Cyanobacteria were frequently observed close-by, as single cells or colonies and heterotrophic bacteria were also found among these. The lithobiontic community showed biogeophysical and biogeochemical effects on the substrate. Cyanobacteria produced bowl- or pear-shaped cavities. Using SEM-BSE and TEM we were able to observe a mineral network structure adjacent to the cyanobacterial wall that might be related to calcium biomobilization processes. Neoformation of biogenic carbonate was detected in thalli of the lichen Thyrea. This information was complemented by observing details of the response of these biological components to the biocidal agents, ALGOPHASE ®, METATIN ® and PREVENTOL R80 ®. After treatment, Thyrea remained on the stone, although ultrastructural alterations were observed in the photobiont. When the effects of the biocides on the ultrastructure of the cyanobacteria were analyzed, ALGOPHASE ® proved to be the least efficient, while PREVENTOL R80 ® led to the complete disorganization of the prokaryotic cyanobacterial cell. These results point to the importance of evaluating biodeterioration processes and possible treatment measures without extracting the microorganisms from their microhabitat.

Plasticizers increase adhesion of the deteriogenic fungus Aureobasidium pullulans to polyvinyl chloride.

Initial adhesion of fungi to plasticized polyvinyl chloride (pPVC) may determine subsequent colonization and biodeterioration processes. The deteriogenic fungus Aureobasidium pullulans was used to investigate the physicochemical nature of adhesion to both unplasticized PVC (uPVC) and pPVC containing the plasticizers dioctyl phthalate (DOP) and dioctyl adipate (DOA). A quantitative adhesion assay using image analysis identified fundamental differences in the mechanism of adhesion of A. pullulans blastospores to these substrata. Adhesion to pPVC was greater than that to uPVC by a maximum of 280% after a 4-h incubation with 10(8) blastospores ml(-1). That plasticizers enhance adhesion to PVC was confirmed by incorporating a dispersion of both DOA and DOP into the blastospore suspension. Adhesion to uPVC was increased by up to 308% in the presence of the dispersed plasticizers. Hydrophobic interactions were found to dominate adhesion to uPVC because (i) a strong positive correlation was observed between substratum hydrophobicity (measured by using a dynamic contact angle analyzer) and adhesion to a range of unplasticized polymers including uPVC, and (ii) neither the pH nor the electrolyte concentration of the suspension buffer, both of which influence electrostatic interactions, affected adhesion to uPVC. In contrast, adhesion to pPVC is principally controlled by electrostatic interactions. Enhanced adhesion to pPVC occurred despite a relative reduction of 13 degrees in the water contact angle of pPVC compared to that of uPVC. Furthermore, adhesion to pPVC was strongly dependent on both the pH and electrolyte concentration of the suspension medium, reaching maximum levels at pH 8 and with an electrolyte concentration of 10 mM NaCl. Plasticization with DOP and DOA therefore increases adhesion of A. pullulans blastospores to pPVC through an interaction mediated by electrostatic forces.

Major impacts made by lichens in biodeterioration processes

For many years, lichens were considered as being of minor importance in terms of their environmental impact, other than in a few extreme ecosystems and habitats where they provided the dominant vegetational cover. Their role as biological weathering agents in the development of soils was formerly considered in a geological context only, but recent research has shown that these organisms are capable of biodeteriorating stone substrata within a relatively short time-scale.