The broad term 'library materials' encompasses a vast range of objects produced by humans over a long period of time and destined for a great variety of uses and expressive aims. They include animal skins, palm leaves, papyrus stems, split bamboo, textiles and practically any support that offers a surface suitable for writing (Bloom, 2017). The invention of paper in 105 A.D., announced by Cai Lun to the Chinese emperor Ho-ti of the Eastern Han dynasty, initiated the establishment of libraries as we know them today, namely places where books are kept, organised and used. However, paper and its widespread use developed quite slowly, hence most of the oldest surviving manuscripts are supported by other materials, parchment in particular (Bloom, 2017). We can therefore say that most of the manuscripts, books and archival documents that have come down to us today are predominantly made of paper or parchment, and sometimes both. Different types of ink were used to write them, and they often incorporate protective and ornamental elements such as pigments, wood, textiles, leather and metals. The study of microorganisms that cause paper and parchment biodeterioration probably began with the generation of microbiologists to which Christian Gottfried Ehrenberg (1795-1876) belonged (Williams et Huxley, 1998). Ehrenberg was a German naturalist and microscopist; he was the first to isolate and describe microfungal species using paper as growth substrate. For example, the fungus Chaetomium chartarum, named by Ehrenberg in 1818, is a cellulolytic fungal species that typically degrades cellulosic substrates, including paper (charta in Latin) (Figure 1). Later, other scholars focused on the study of paper biodeterioration at a time when the rigour of attributing a cause to an effect, summarised by Kock's postulates (Grimes, 2006), pervaded all areas of microbiology, even those in which the 'patient' was non-living matter such as paper or leather. Koch's postulates consist of four criteria intended to establish a causative relationship between a microbe and a disease: 1) the microorganism must be present in every case of the 'disease'; 2) it must be isolated from the host presenting with the disease and grown in pure culture; 3) the specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host; 4) the microorganism must be re-isolated from the inoculated, diseased experimental host and identified as identical to the original specific causative agent. The postulates were published by Koch in 1890 to describe the aetiology of cholera and tuberculosis and were subsequently applied to other diseases. From the 1920s onwards, and for at least 60 years of library materials' microbiology thereafter, the study of biodeterioration was based on the belief that for every type of damage there was a specific culprit, and in many investigations authors strenuously sought to refer to Kock's postulates to prove that isolated organisms were the real cause of the observed damage. This approach has sometimes worked, but not always. In 1997 Zyska reviewed the list of filamentous fungi associated with library materials' biodeterioration and found that 234 species belonging to 84 genera were isolated between 1919 and 1977 from a range of materials, not only paper or parchment (Zyska, 1997), and stressed how most of these organisms were also present in the air of Polish archives. He also lamented the lack of interest in isolating library materials bio-deteriorating organisms by culture in collections worldwide. As a matter of fact, the importance of controlling environmental conditions in preventing biodeterioration was recognised early on as the first, if not the only weapon against damage-causing phenomena, in conjunction with frequent monitoring of collections and dusting, so as to protect books from deterioration (Gallo, 1993). Pinheiro et al. (2019) reviewed 71 studies, dating from 1997 to 2018, on microfungal populations found in paper-based collections across the world. The authors reported 580 species belonging to 207 fungal genera from 27 different countries. The studies reviewed by the authors included both those in which fungi were isolated from the material and those in which the association with the material was made by culturing-free methods. In more complex contexts such as soil, water and other natural environments it has been shown that culturing methods recover less than 1% of the total microorganisms present (Amann et al. 1995, Ward et al. 1990), and just 5% of fungal species can be described, owing to culture limitations and misidentifications (Hawksworth and Rossman 1997). According to Ritz (2007), the application of culturing techniques to isolate putatively environmentally-active microorganisms, or to characterise the biodiversity of microbial communities was 'not appropriate and no longer admissible!' and when speaking of the use of fungal colony-forming units measurement in an ecological sense 'any attempt to quantitatively describe a fungal community using this metric is very limited.' Indeed, the application of molecular techniques for the study of materials biodeterioration has produced some surprising results. Early studies based on denaturing gradient gel electrophoresis (DGGE) fingerprints and cloning (Michaelsen et al., 2006, 2009, 2010) revealed high biodiversity of both bacteria and fungi inhabiting biodeteriorated books, and DNA sequence analysis confirmed the coexistence of several fungi and bacteria in both paper and parchment samples (Pinar et al., 2015; Migliore et al., 2017) (Figure 1). So far, in culture-independent studies of paper biodeterioration, a surprisingly large number of bacterial and fungal species have been identified -- many more than initially imagined -- and, indeed, too many to be responsible for the biodeterioration mechanism (Sterflinger et al., 2018, Pinzari, 2018). With the more recent works based on massive sequencing techniques, from which lists of species are obtained that also include organisms present on the material as mere occasional contaminants, problems have also begun to arise (Figure 1). Discerning which of the many organisms are active or have caused the damage to the material is a far from easy task, and often having a very long list of potential suspects does not make matters easier (Sterflinger et al., 2018). We are currently at a stage in the study of the microbiology of book biodeterioration where, despite there being a vast amount of information that can be obtained, there is often a lack of effective tools to integrate this information. What routes are reliable and how can research be continued effectively in the field of library assets biodeterioration prevention? How can we cope with the deluge of information that modern techniques provide? (Sterflinger et al., 2018, Pinzari, 2018; Pinzari and Gutarowska, 2021). From the beginning of 2020, another microbiology-related concern emerged in the field of book and paper conservation and among general libraries and archives' personnel. The ongoing COVID-19 pandemic is causing fear of contagion linked to the handling of documents in libraries and archives, since materials can potentially carry the virus. This subject, which will be discussed later on, represents an additional microbiological challenge to researchers and conservators, not only with respect to understanding the real risks involved, but also in relation to knowing how to mitigate them.
Degradation, remediation and protection of library materials
Pinzari F;
2022
Abstract
The broad term 'library materials' encompasses a vast range of objects produced by humans over a long period of time and destined for a great variety of uses and expressive aims. They include animal skins, palm leaves, papyrus stems, split bamboo, textiles and practically any support that offers a surface suitable for writing (Bloom, 2017). The invention of paper in 105 A.D., announced by Cai Lun to the Chinese emperor Ho-ti of the Eastern Han dynasty, initiated the establishment of libraries as we know them today, namely places where books are kept, organised and used. However, paper and its widespread use developed quite slowly, hence most of the oldest surviving manuscripts are supported by other materials, parchment in particular (Bloom, 2017). We can therefore say that most of the manuscripts, books and archival documents that have come down to us today are predominantly made of paper or parchment, and sometimes both. Different types of ink were used to write them, and they often incorporate protective and ornamental elements such as pigments, wood, textiles, leather and metals. The study of microorganisms that cause paper and parchment biodeterioration probably began with the generation of microbiologists to which Christian Gottfried Ehrenberg (1795-1876) belonged (Williams et Huxley, 1998). Ehrenberg was a German naturalist and microscopist; he was the first to isolate and describe microfungal species using paper as growth substrate. For example, the fungus Chaetomium chartarum, named by Ehrenberg in 1818, is a cellulolytic fungal species that typically degrades cellulosic substrates, including paper (charta in Latin) (Figure 1). Later, other scholars focused on the study of paper biodeterioration at a time when the rigour of attributing a cause to an effect, summarised by Kock's postulates (Grimes, 2006), pervaded all areas of microbiology, even those in which the 'patient' was non-living matter such as paper or leather. Koch's postulates consist of four criteria intended to establish a causative relationship between a microbe and a disease: 1) the microorganism must be present in every case of the 'disease'; 2) it must be isolated from the host presenting with the disease and grown in pure culture; 3) the specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host; 4) the microorganism must be re-isolated from the inoculated, diseased experimental host and identified as identical to the original specific causative agent. The postulates were published by Koch in 1890 to describe the aetiology of cholera and tuberculosis and were subsequently applied to other diseases. From the 1920s onwards, and for at least 60 years of library materials' microbiology thereafter, the study of biodeterioration was based on the belief that for every type of damage there was a specific culprit, and in many investigations authors strenuously sought to refer to Kock's postulates to prove that isolated organisms were the real cause of the observed damage. This approach has sometimes worked, but not always. In 1997 Zyska reviewed the list of filamentous fungi associated with library materials' biodeterioration and found that 234 species belonging to 84 genera were isolated between 1919 and 1977 from a range of materials, not only paper or parchment (Zyska, 1997), and stressed how most of these organisms were also present in the air of Polish archives. He also lamented the lack of interest in isolating library materials bio-deteriorating organisms by culture in collections worldwide. As a matter of fact, the importance of controlling environmental conditions in preventing biodeterioration was recognised early on as the first, if not the only weapon against damage-causing phenomena, in conjunction with frequent monitoring of collections and dusting, so as to protect books from deterioration (Gallo, 1993). Pinheiro et al. (2019) reviewed 71 studies, dating from 1997 to 2018, on microfungal populations found in paper-based collections across the world. The authors reported 580 species belonging to 207 fungal genera from 27 different countries. The studies reviewed by the authors included both those in which fungi were isolated from the material and those in which the association with the material was made by culturing-free methods. In more complex contexts such as soil, water and other natural environments it has been shown that culturing methods recover less than 1% of the total microorganisms present (Amann et al. 1995, Ward et al. 1990), and just 5% of fungal species can be described, owing to culture limitations and misidentifications (Hawksworth and Rossman 1997). According to Ritz (2007), the application of culturing techniques to isolate putatively environmentally-active microorganisms, or to characterise the biodiversity of microbial communities was 'not appropriate and no longer admissible!' and when speaking of the use of fungal colony-forming units measurement in an ecological sense 'any attempt to quantitatively describe a fungal community using this metric is very limited.' Indeed, the application of molecular techniques for the study of materials biodeterioration has produced some surprising results. Early studies based on denaturing gradient gel electrophoresis (DGGE) fingerprints and cloning (Michaelsen et al., 2006, 2009, 2010) revealed high biodiversity of both bacteria and fungi inhabiting biodeteriorated books, and DNA sequence analysis confirmed the coexistence of several fungi and bacteria in both paper and parchment samples (Pinar et al., 2015; Migliore et al., 2017) (Figure 1). So far, in culture-independent studies of paper biodeterioration, a surprisingly large number of bacterial and fungal species have been identified -- many more than initially imagined -- and, indeed, too many to be responsible for the biodeterioration mechanism (Sterflinger et al., 2018, Pinzari, 2018). With the more recent works based on massive sequencing techniques, from which lists of species are obtained that also include organisms present on the material as mere occasional contaminants, problems have also begun to arise (Figure 1). Discerning which of the many organisms are active or have caused the damage to the material is a far from easy task, and often having a very long list of potential suspects does not make matters easier (Sterflinger et al., 2018). We are currently at a stage in the study of the microbiology of book biodeterioration where, despite there being a vast amount of information that can be obtained, there is often a lack of effective tools to integrate this information. What routes are reliable and how can research be continued effectively in the field of library assets biodeterioration prevention? How can we cope with the deluge of information that modern techniques provide? (Sterflinger et al., 2018, Pinzari, 2018; Pinzari and Gutarowska, 2021). From the beginning of 2020, another microbiology-related concern emerged in the field of book and paper conservation and among general libraries and archives' personnel. The ongoing COVID-19 pandemic is causing fear of contagion linked to the handling of documents in libraries and archives, since materials can potentially carry the virus. This subject, which will be discussed later on, represents an additional microbiological challenge to researchers and conservators, not only with respect to understanding the real risks involved, but also in relation to knowing how to mitigate them.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
