biodeterioration

Valuable cultural heritage is always exposed to the invasion of biological agents and the resulting destruction, especially when the physical and chemical conditions of the work and its surrounding environment are compatible with the characteristics of an organism or a microorganism. Therefore, preventing the occurrence of such conditions and limiting the invasion of biological agents should be among the main and primary goals of every center. Over the years, various methods such as the use of disinfectants have been used to control biological agents in various historical and cultural collections. With the passage of time and increasing awareness of the harmful effects of these substances on the treated works, the environment and the users, nowadays the use of non-toxic alternative methods is more recommended. Experience has shown that the method that causes the least damage to collections and employees is preventive methods and regular control, which is possible through monitoring and managing the environment. Integrated pest management with the ultimate goal of removing harmful biological agents from a place is one of the long-term preventives and non-toxic methods of controlling biological agents that is used in many museums, archives, and libraries. In this article, along with a brief overview of biological deterioration and its preventive and control strategies, microbiological monitoring of the air inside 4 storerooms in the world heritage complex of Golestan Palace Museum including: the anthropological clothing, the manuscripts, the carpets, and the Painting storerooms was carried out. For this purpose, air sampling was done by sedimentation method and isolated microbial colonies on the culture media were investigated and identified. The results of the microbiological monitoring of the air inside the storerooms in this study showed that except for the carpet storeroom, other studied storerooms, including the anthropological clothing, the manuscript and the painting storerooms, are acceptable in terms of the number of microorganisms in the air.

The World Heritage of Gonbad-e Qābus tower, as one of the architectural masterpieces of the Islamic period of Iran, has been exposed to various biological growths and invasions in the open air. This study aims to identify the type of biological agents living on the ancient brick surfaces in Gonbad-e Qābus tower in Gonbad-e kāvus city in Golestan province. In this research, using field observations, in-site macroscopic observations, microscopic methods, and library studies, biological factors were identified and influenced on the brick surface of the Qaboos dome in three parts: foundation, body, and dome. Based on this, the biodeterioration factors were divided into two sampling groups. The first group includes macro-organisms, which was done to prevent damage based on the identification method based on documentation and camera photography. The second group is the sampling of microorganisms such as bacteria and fungi, microalgae and cyanobacteria, lichens, which are sampled from the brick surface with sterile tweezers and then transferred into the microtube and by the method morphology, culture and microscopy were identified. In general, nine groups of organisms responsible for biodeterioration were identified in this study, among their main groups are bacteria, cyanobacteria and algae, fungi, lichens, mosses and plants, insects and small animals. Macro-organisms increase and decrease with changes in humidity and are therefore effective in the mechanical destruction of substrate components. Among the macro-organisms, plants and mosses were known to be the most important enemies of the existing brick substrate of Gonbad-e Qābus tower. Microorganisms are able to form clones and biofilms on the surface of the brick substrate. They secrete acids that break down the minerals that make up the brick substrate and thus play an important role in the biodeterioration of the building. In general, the bricks of the exterior walls of the building are exposed to the attack of various biological and non-living factors and generally show less resistance to the activities of wear factors. Humidity, temperature and light and urban dust pollution are potential factors in increasing the factors involved in biodeterioration can be discussed in future researches.

Fungi play a significant role in the deterioration of cultural heritage. Due to their high enzyme activity, fungi are able to inhabit and destroy the various materials used for historical objects. Because of the cellulose structure of the paper, paper works in archival documents are very vulnerable to damage by microorganisms, including fungi, and they are always faced with the problem of biodeterioration. Considering the harmful effects of using chemicals on paper works as well as their toxic effect on museum curators and conservators in museum collections and libraries, it is very necessary to find a suitable alternative to deal with destructive fungi. In this regard, the use of herbal essential oils has always been considered. Considering the diversity and abundance of medicinal plants in our country, Iran, in this study, the antifungal effect of the essential oils of three plants including Thymus, Lavender, and Boswellia was evaluated against two common fungal strains isolated from historical documents, including Penicillium and Aspergillus niger. Also, the possible physical and chemical effects of these essential oils on paper were studied to determine which essential oil can be the most suitable option for the decontamination of paper documents.The results obtained in this study confirm that the three investigated essential oils have antifungal activity. But based on the dose required for antimicrobial activity, it can be said that thymus essential oil has more antifungal activity than lavender and Boswellia essential oil. Due to the thymus’s high antimicrobial effect and also the absence of adverse effects on pH and physical properties on paper, it can be a suitable and promising option for protecting paper documents against fungal biodeterioration.

Microbial colonization of cultural heritage objects is inevitable. Microorganisms cause physical, chemical, and aesthetic alteration in valuable works of art, leading to the loss of both financial and cultural value. To prevent and control microbial colonization and their growths, physical, chemical, and biological methods are used. However, physicochemical methods are often ineffective on treated works of art, and can be dangerous for people involved in the conservation process. Due to inherent characteristics, chemical compounds and biocides, they are hazardous for humans, animals, and the environment. Given the significant weaknesses of these conventional methods, new approaches are continuously being developed to reduce the negative impact of deteriogenic microorganisms. These new approaches are environmentally friendly, safe, low-cost and low-risk. However, more research is needed to monitor the safety and effectiveness of these approaches. The lack of simple, reliable and standard measurements remains a limitation in the selection ofeffective treatments. Field experiments are necessary and useful for evaluating the effectiveness of these methods however, their design and implementation face several challenges. Therefore, researchers are seeking to develop methods to investigate how these new approaches work. Laboratory model systems are tools for testing the efficacy of antimicrobial compounds before field application on art works. In this study, we will first review the types of biological control methods, and then introduce the new and environmentally friendly approaches, that have been developed in this field. Finally, we will discuss methods of testing the effectiveness of new strategies using laboratory model systems.

Biological contamination of paper artifacts is a significant threat, causing not only damage to the paper itself but also posing health risks to conservators and restorers who are in close contact with them. Therefore, identifying the type of contamination is crucial for effective preservation and restoration. This article focuses on identifying biological contamination in a collection of paper artifacts from the Imamzadeh Mohammad in Tafresh, Iran. Preliminary examinations revealed evidence of biological contamination, including stains resulting from biological activity. These stains are a consequence of biodeterioration, leading to a reduction in the structural and artistic quality of the artifacts. To investigate the biological contamination, samples were taken from areas suspected of contamination and cultured on Sabouraud dextrose agar (for fungal contamination) and nutrient agar (for bacterial contamination). After incubation, the grown colonies were examined and identified. The results of the identification of isolated fungal and bacterial showed contamination with various fungi, including Penicillium, Aspergillus, Cladosporium, and yeasts, as well as bacteria belonging to the Actinomycetes and Bacillus genus.

Cultural heritage has always been the focus of many civilizations and therefore, it needs to be preserved for future generations. From prehistoric times, when grandeur and beauty were the aims of architecture, stone was the most widely used durable material. Biodeterioration of the stone monuments, one of the most important causes for the loss of the cultural heritage, is defined as any undesirable change in the properties of a material caused by the action of biological agents such as fungi, bacteria, cyanobacteria, lichens and plants, as well as animals such as insects. The world heritage of Persepolis, for example, has been unprotected from biodeterioration for the centuries, and has unfortunately not been addressed during this time. The purpose of this study is to provide a new perspective on the study of the destructive biological factors affecting this historic site to provide a framework for future studies and serious consideration of the biological debate in conservation and restoration issues. Therefore, the presence of various factors possibly derived from the action of animals, vascular plants, mosses, fungi, lichens, green microalgae, and photosynthetic and non-photosynthetic bacteria were investigated. Based on objective observations, the presence of biodegradation factors affecting floors and the all sides of walls of various buildings in Persepolis was qualitatively investigated. Based on the results, the studied areas were classified into four classes with very high, high, medium and low risk. In addition to the initial estimate of biodiversity, the factors affecting the biodegradation of Persepolis were presented for the first time and the critical points for the presence of destructive factors were determined. Lichens exist throughout Persepolis and have proved useful in archaeological studies, since their growth can be chronologically employed to measure the age of rocks and indeed ancient monuments, their radial growth increasing logarithmically over time based on the assumed specific rate. In this study, the presence of lichens has been investigated from the perspective of biodeterioration, their presence at the microscopic scale can intensify the weathering and biodeterioration of the rock. Such action is not visible to the naked eye but leaves irreparable damage to the stone surface. It was estimated that this complex process at Persepolis is the result of more than 15 different Vascular plant species and 5 Non-vascular plant (mosses), 16 or 17 different species of birds, 3 to 5 species of snails and 2 to 4 species of reptiles and insects. It was shown that the establishment of a biomonitoring laboratory at Persepolis is the important task of studying the action of microorganisms since it is estimated that more than 20 strains of non-photosynthetic bacteria, more than 10 taxa of cyanobacteria, about 15 plants and mosses, more than 130 lichen species and 20 species of non-lichen fungi are involved in the biodegradation of Persepolis. The results are the estimative and provide the basis for more detailed studies to monitor the factors involved in biodegradation, which is one of the necessities of this World Heritage Site.