Microbial deterioration of gelatin emulsion photographs: Differences of susceptibility between black and white and colour materials

Microbial deterioration is a common problem in photographic collections, and has been considered a major cause of deterioration. However, few studies have been carried out on this topic, and most of the literature concerns biodeterioration of archival documents in general, including both micro- and macroorganisms. There have been no detailed studies on the interactions between microorganisms, environment, and the composition of photographic material. This study focuses on fungal deterioration of gelatin emulsion photographs. It was part of a study of three collections in Lisbon, Portugal. The first part is quantitative research on the fungal contamination of the Horácio Novais collection, and the second involves induced contamination of experiments on gelatin emulsion photographs. At the end these data are analysed, taking into account the hypothesis that colour materials are more susceptible to fungal deterioration than are black and white ones. This hypothesis is based on the observations of professionals working with photograph collections who report that, at least in plastic base supports (negatives and slides), colour materials are frequently more contaminated than the black and white ones. An overall look at the results seems to indicate a higher susceptibility of the colour chromogenic photographic materials to fungal colonization compared to the black and white materials. However, this hypothesis could not be absolutely confirmed by this study.     

A viscometric study of the biodegradation of photographic gelatin by fungi isolated from cinematographic films

The biodegradation of photographic gelatin grade (Bloom 225) material was studied by viscometry in aqueous solution (at 37 °C, 6.67% w/w) using filamentous fungi isolated and identified from cinematographic film stored in different Spanish archives. From viscosity data, different variables such as molecular weight and chain scission were calculated. To ensure initial spore suspension concentration was standardized for all the biodegradation experiments, a correlation between transmittance at 530 nm of fungal spore suspensions and the corresponding cytometric determination of populations was established for all the fungal strains studied in this work. The bioassay experiments were carried out at 25 and 4 °C using an initial concentration of fungi of 4.5×10⁵ conidia/mL except in the case of the genus Alternaria, where the concentration was 10 times lower. The fungal strains were three species of Aspergillus, i.e., A .ustus, A. nidulans var. nidulans, A. versicolor, seven Penicillium chrysogenum strains, and Cladosporium cladosporioides, Alternaria alternata, Mucor racemosus, Phoma glomerata, and Trichoderma longibrachiatum. All were gelatinase positive. Through the viscosity decay profiles with bioassay-time and the corresponding calculated chain scission, the relative quantitative gelatinase efficiency of these fungi has been evaluated.     

Biodeterioration of external architectural paint films - A review

This paper presents a review of the biodeterioration of architectural paint films by bacteria, fungi and algae, concentrating on external films. 107 references are cited in the following sections: 1. Microbiota of paint films - resident microflora, colonization and biofilm formation; 2. Effects of environment on biofilm formation and survival; 3. Influence of paint formulation on colonization - basic paint components, pigment volume content (PVC), pigments, biocides; 4. Effects of painted substrate on susceptibility; 5. Instrumental methods used in the analysis of paint film biodeterioration - vibrational spectroscopy, laser-induced breakdown spectroscopy, HPLC, image analysis, FTIR spectroscopy, GC-MS; 6. New technologies in the coatings industry - photocatalytic layers, cool paints, silver nanoparticles, silicon-containing paints.     

Fungal biosorption of silver particles on 20th-century photographic documents

Microbial deterioration is a common problem in photographic collections and is considered a major cause of loss of documents. However, few studies so far have been addressed to biological damage on these materials. Several species of naturally occurring fungi can cause infections on the gelatin-silver emulsion of both positive and negative photographic material, producing defacement and loss of mechanical and aesthetical properties of the objects. In this study a particular phenomenon, spontaneously caused by fungi on 20th-century photographic films and positive supports, was documented by means of variable pressure scanning electron microscopy (VP-SEM) combined with electronic dispersion spectroscopy (EDS). This technique allowed the observation of entire, unaltered films without metallisation thus with a not invasive approach. The ability of some fungi to alter the distribution of silver crystals in the gelatin emulsion was described thanks to a backscattered electrons detector that showed differences in the atomic number of the visualised objects, giving rise to an appreciable contrast in case of different chemical composition.     

Synthetic Consolidants Attacked by Melanin-Producing Fungi: Case Study of the Biodeterioration of Milan (Italy) Cathedral Marble Treated with Acrylics

Monuments and artistic stone surfaces are often consolidated and protected with synthetic polymers, in particular, acrylics. Although it is generally thought that acrylic polymers are resistant to biodeterioration, we report for the first time the systematic occurrence of dematiaceous meristematic fungi on many marble samples of the cathedral in Milan (Italy) previously treated with this material. Fourier transform infrared spectroscopy applied to the Milan cathedral stone samples revealed characteristic features of biodeteriorated synthetic resins that differentiated them from the aged but nonbiodeteriorated samples. Samples showing biological colonization were analyzed for the presence of fungi. Cultivation and morphological characterization and methods independent from cultivation, such as denaturing gradient gel electrophoresis coupled with partial 18S rRNA gene sequencing and immunofluorescence staining with melanin-binding antibodies, showed that melanin-producing species are heavily present on stone surfaces protected with acrylic resins. This observation raises the question of the effectiveness of acrylics in protecting stone artworks.     

Indirect effects of a non-target species, Pyrrhalta luteola (Chrysomelidae) on the biodeterioration of Brussels tapestries

Treatments to preserve artwork are usually designed to control for known target species. Nevertheless, indirect effects of non-target species may cause important biodeterioration. During the restoration of a series of Brussels tapestries preserved in the Abbey of Sacromonte (Granada, Spain), we studied one of the tapestries which presented a high degree of deterioration, principally large losses of material and color alterations. We found important biodeterioration effects produced by a non-target insect species, the beetle Pyrrhalta luteola (Chrysomelidae). We raised P. luteola beetles in the laboratory on different constituent materials to identify the effects of this insect on the tapestry. Results showed that beetle remains were mainly responsible for the chromatic changes. Although beetles did not consume textile materials, and had not direct effects in tapestry destruction, its presence indirectly affected the tapestry due to the higher mold-growth obtained in samples of materials with beetle remains. Based on these results, we propose some recommendations to consider control for these potential biodeterioration agents in artwork conservation programs.     

Synthetic consolidants attacked by melanin-producing fungi: case study of the biodeterioration of Milan (Italy) cathedral marble treated with acrylics

Monuments and artistic stone surfaces are often consolidated and protected with synthetic polymers, in particular, acrylics. Although it is generally thought that acrylic polymers are resistant to biodeterioration, we report for the first time the systematic occurrence of dematiaceous meristematic fungi on many marble samples of the cathedral in Milan (Italy) previously treated with this material. Fourier transform infrared spectroscopy applied to the Milan cathedral stone samples revealed characteristic features of biodeteriorated synthetic resins that differentiated them from the aged but nonbiodeteriorated samples. Samples showing biological colonization were analyzed for the presence of fungi. Cultivation and morphological characterization and methods independent from cultivation, such as denaturing gradient gel electrophoresis coupled with partial 18S rRNA gene sequencing and immunofluorescence staining with melanin-binding antibodies, showed that melanin-producing species are heavily present on stone surfaces protected with acrylic resins. This observation raises the question of the effectiveness of acrylics in protecting stone artworks.     

Thin liquid films and monolayers of DMPC mixed with PEG and phospholipid linked PEG

In this work thin liquid films (TLFs) and monolayers at the air/water interface formed by dimyristoylphosphatidylcholine (DMPC) and by DMPC mixed with poly ethylene glycols (PEGs) and dimyristoylphosphatidylethanolamine (DMPE) linked PEGs were studied. Film forming dispersions were composed of two types of particles: liposomes and micelles. TLFs stability, threshold concentration C _t (i.e., the minimum one for stable film formation), and hydrodynamic behavior were measured. At equivalent conditions, DMPC films were Newton black films (real bilayers), while DMPE-PEGs films were much thicker with free water between the monolayers. DMPE-PEG addition to DMPC films caused both C _t decrease (depending on PEG moiety length and Mw) and change of TLF formation mechanism. TLFs’ hydrodynamic behavior also strongly depended on DMPE-PEG content and Mw. It was observed that thinning of the DMPC and DMPE-PEGs films continued to different film types and thickness, being much thicker for the latter films. Addition of free PEGs (PEG-200/6000) did not alter TLF type or stability, but changed TLF thinning time, confirming that free PEGs with Mw<8000 could not penetrate in the membrane and alter “near-membrane” water layer viscosity. Monolayer studies showed improved formation kinetics of both adsorbed and spread films, decrease of surface tension (equilibrium and dynamic), and of film compression/decompression histeresis area in DMPE-PEGs monolayers compared with DMPC pure films. Our study shows that combining the models of phospholipid TLFs and monolayers provide the opportunity to investigate the properties of membrane surface and to clarify some mechanisms of its interactions with membrane-active agents.     

A colorimetric assay for gellan elaborated by Sphingomonas paucimobilis ATCC 31461

A colorimetric assay involving the dye toluidine blue O was developed to determine the concentration of the microbial heteropolysaccharide gellan elaborated by Sphingomonas paucimobilis ATCC 31461. Colour formation was linear up to a concentration of 0.7 mg/ml. The concentration of gellan produced in S. paucimobilis cultures was quantitated using this colorimetric dye-binding assay as well as the currently utilized gravimetric procedure, and comparable results were observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biodegradation of ivory (natural apatite): possible involvement of fungal activity in biodeterioration of the Lewis Chessmen

Fungal biodeterioration of ivory was investigated with in vitro inoculation of samples obtained from boar and walrus tusks with the fungi Aspergillus niger and Serpula himantioides, species of known geoactive abilities. A combination of light and scanning electron microscopy together with associated analytical techniques was used to characterize fungal interactions with the ivory, including changes in ivory composition, dissolution and tunnelling, and the formation of new biominerals. The research was aimed at providing further understanding of the potential roles of fungi in the colonization and deterioration of ivory in terrestrial environments, but also contributes to our knowledge regarding the possible origins of the surface damage observed on early medieval sculptures made largely from walrus tusks, referred to as ‘the Lewis hoard of gaming pieces’, that were presumably produced for playing chess. The experiments have shown that the possibility of damage to ivory being caused by fungi is realistic. Scanning electron microscopy revealed penetration of fungal hyphae within cracks in the walrus tusk that showed also widespread tunnelling by fungal hyphae as well as ‘fungal footprints’ where the surface was etched as a consequence of mycelial colonization. Similar phenomena were observed with boar tusk ivory, while production of metabolites could lead to complete dissolution of the sample. Colonization of ivory and/or exposure to fungal activity lead to extensive secondary biomineral formation, and this was identified as calcium oxalate, mainly as the monohydrate, whewellite.     

Algal growth inhibition on cement mortar: Efficiency of water repellent and photocatalytic treatments under UV/VIS illumination

Building materials are regularly affected by the growth of microalgae. The consequences are mainly aesthetic but the colonization can cause biodeterioration of the material in the most extreme cases. This study investigates two building material treatments that can potentially inhibit or slow down such growth: photocatalytic coatings and water repellent treatments. The efficiency of these treatments in terms of biological growth inhibition was tested on the algae species Graesiella emersonii. Algal growth on building materials was investigated using two accelerated tests simulating different types of humidification (water capillary ascent and water run-off) under different lighting conditions. Mortars treated with photocatalytic coating or with water repellent were studied. The algal growth on the mortar surface was evaluated using image analysis (area covered and intensity of fouling). No slow down of the biological growth kinetics could be attributed to photocatalytic substrates. However, for mortars impregnated with a water-repellent preparation, algal growth slowed significantly under water run-off and even stopped under water capillary ascent.     

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.     

Toward an accelerated biodeterioration test to understand the behavior of Portland and calcium aluminate cementitious materials in sewer networks

Sewer networks contain many aggressive and corrosive agents for pipe materials. One type of damage can be ascribed to concrete corrosion by biogenic sulfuric acid. According to field data, cementitious materials have different behaviors depending in particular on cement type: Those made with calcium aluminate cement (CAC) offer better performance than those made of ordinary Portland cement (OPC). The development of an accelerated and accurate laboratory test is essential to better understand the mechanisms involved for all cementitious materials. However, to define such a test, some additional knowledge is required. The present study deals with in situ experiments in order to determine the biochemical parameters influencing the behaviors of OPC and CAC materials. Based on these determinations, supplemented by laboratory studies, it can be concluded that abiotic oxidation of hydrogen sulfide, bioreceptivity of the mineral surface, and growth of bacterial strains depend greatly on cementitious material types. All these results, complemented by literature data, lead to consideration of what the best parameters are to study biodeterioration of cementitious materials, and have been helpful in designing the biodeterioration chamber tested.     

Biodegradation of triphenylmethane dye Malachite Green by <Emphasis Type="Italic">Sphingomonas paucimobilis</Emphasis>

Triphenylmethane dyes belong to the most important group of synthetic colorants and are used extensively in the textile industries for dying cotton, wool, silk, nylon, etc. They are generally considered as the xenobiotic compounds, which are very recalcitrant to biodegradation. Sphingomonas paucimobilis, was isolated from the soil sample collected from contaminated sites of textile industry located in KsarHellal, Tunisia, and it was able to decolorize Malachite Green (MG) dye (50 mg/l) within 4 h under shaking condition (pH 9 and temperature 25°C). The effect of inoculum size, dye concentration, temperature and initial pH of the solution were studied. The results obtained from the batch experiments revealed the ability of the tested bacteria to remove dye. UV–Vis spectroscopy and FTIR analysis of samples before and after decolorization confirmed the ability of the tested strain to decolorize MG. In addition, the phytotoxicity study revealed the degradation of MG into non-toxic product by S. paucimobilis.     

Interaction of gum arabic, maltodextrin and pullulan with lipids in emulsions

The interaction of gum arabic, maltodextrin and pullulan with lipids in emulsion systems was investigated. Interfacial tension and interfacial viscosity measurements revealed that only gum arabic could adsorb and form a viscoelastic film at the oil-water interface. Good emulsifying activity was demonstrated for gum arabic, whereas fine emulsions could not be produced from the other polysaccharide solutions and oil. Frequency-dependent increases in the storage and loss moduli were observed for all the polysaccharide solutions. Such rheological behavior did not substantially change when maltodextrin and pullulan were mixed with oil to form emulsions. However, the frequency-dependence of the dynamic moduli disappeared in the gum arabic-stabilized emulsion, suggesting the formation of a network structure in which oil droplets could form junctions with gum arabic chains. The results on the inhibition of lipid oxidation by polysaccharides suggest that gum arabic protected lipids from the attack of lipoxygenase and free radicals by adsorbing at the oil droplet surface.     

Antioxidative activity,moisture retention,film formation,and viscosity stability of Auricularia fuscosuccinea,white strain water extract

This study showed that both water extracts (WAF-W) and ethanol extracts (EAF-W) of Auricularia fuscosuccinea (Montagne) Farlow, white strain (AF-W) demonstrated significantly stronger antioxidative effects than did commercially available Tremella fuciformis sporocarp extracts (WSK; with the exception of EAF-W in terms of superoxide radical scavenging activity levels). The moisture retention capacity of WAF-W is as potent as that of sodium hyaluronate (SHA), but less than that of WSK. No corrugation or fissures were observed in WAF-W film; only the SHA and WSK films demonstrated such effects in low-moisture conditions. The WAF-W solution also exhibited stable viscosity at high temperatures, indicating that the WAF-W film was more stable compared with the SHA and WSK films. WAF-W induced no adverse effects when a hen’s egg test was performed on the chorioallantoic membrane (CAM). This study demonstrated that WAF-W exhibits excellent potential as a topical material for skin moisturizing and anti-aging effects.     

Pyronin Y For Staining Stripped Autoradiographs Prepared from Plastic Embedded Sections of Rat Tissues Containing Plutonium

Autoradiography prepared by the stripping film technique from 1 μm sections of semithin plastic embedded liver and bone tissues were poststained for examination with a 1% pyronin Y solution. The use of this dye avoids heating the tissue section and the overlying photographic emulsion. It also allows the staining of the tissue section without excessive uptake of the stain by the gelatin of the stripping film.     

Rectified photocurrent of molecular photodiode consisting of cytochrome c/GFP hetero thin films

Photoinduced electron transfer in the molecular electronic device consisting of protein-adsorbed hetero Langmuir–Blodgett (LB) film was investigated. Three kinds of functional molecules, cytochrome c, viologen, and green fluorescent protein (GFP) were used as an electron acceptor, a mediator, and a sensitizer, respectively. The hetero-LB film was fabricated by subsequently depositing cytochrome c and viologen onto the pretreated ITO or quartz glass. GFP adsorbed hetero-LB films were prepared by soaking the hetero-LB films into the buffer solution containing GFP. The MIM (metal/insulator/metal) structured molecular device was constructed by depositing aluminum onto the surface of the GFP-adsorbed hetero LB films. Due to the excitation by irradiation with a 460 nm monochromic light source, the photoinduced unidirectional flow of electrons in the MIM device could be achieved and was detected as photocurrents. The photoswitching function was achieved and the rectifying characteristic was observed in the molecular device. Based on the measurement of transient photocurrent of molecular device, the unidirectional flow of electrons was verified.     

Microbial deterioration of cultural heritage and works of art — tilting at windmills?

Microorganisms (bacteria, archaea and fungi), in addition to lichens and insect pests, cause problems in the conservation of cultural heritage because of their biodeteriorative potential. This holds true for all types of historic artefacts, and even for art made of modern materials, in public buildings, museums and private art collections. The variety of biodeterioration phenomena observed on materials of cultural heritage is determined by several factors, such as the chemical composition and nature of the material itself, the climate and exposure of the object, in addition to the manner and frequency of surface cleaning and housekeeping in museums. This study offers a review of a variety of well-known biodeterioration phenomena observed on different materials, such as stone and building materials, objects exhibited in museums and libraries, as well as human remains and burial-related materials. The decontamination of infected artefacts, exhibition rooms and depots incurs high expenditure for museums. Nevertheless, the question has to be raised: whether the process of biodeterioration of cultural heritage can or should be stopped under all circumstances, or whether we have to accept it as a natural and an implicit consecution of its creation. This study also highlights critically the pros and cons of biocide treatments and gives some prominent examples of successful and unsuccessful conservation treatments. Furthermore, an outlook on the future research needs and developments in this highly interesting field is given.     

Improvement in Production and Quality of Gellan Gum by Sphingomonas paucimobilis Under High Dissolved Oxygen Tension Levels

The effect of agitation rate and dissolved oxygen tension (DOT) on growth and gellan production by Sphingomonas paucimobilis was studied. Higher cell growth of 5.4 g l⁻¹ was␣obtained at 700 rpm but maximum gellan (15 g l⁻¹) was produced at 500 rpm. DOT levels above 20% had no effect on cell growth but gellan yield was increased to 23 g l⁻¹ with increase in DOT level to 100%. Higher DOT levels improved the viscosity and molecular weight of the polymer with change in acetate and glycerate content of the polymer.