Investigation of the Autochthonous Microbiota of Parchment and Identification of Potential Microbial Reasons for Decay
Individual Research Project
Parchment production involves a series of distinct processing steps. Historically widespread in Western Asia and Europe, these steps typically include skinning, soaking, salting, hair removal, stretching, and the final scraping to remove remaining residues. The animal skins used for parchment are usually derived from cattle, sheep, or goats. The structural integrity of parchment is provided by collagen fibres, which, during production, are partially denatured and hydrolysed, forming a rigid, gel-like network. However, deterioration of parchment and exposure to high temperatures can compromise the integrity of the manuscripts, leading to their decay.
Natural surfaces are colonised by various microorganisms, collectively referred to as the microbiota. A distinct microbiota may also be found on parchment manuscripts. This microbiota primarily consists of bacteria, fungi, and yeasts. Some members of the microbiota are capable of producing collagenases, which can degrade collagen fibres. Structural disruption facilitates microbial proteolysis, and microbial decay can be visible through discolouration, cockling, or loss of parchment material. While parchment production may influence the composition of the microbiota, handling, storage, and environmental factors can alter the indigenous microorganisms over its lifetime. This project focuses on the microbiota of parchment manuscripts, as analysed in a previous study within the context of the Kairouan Manuscript Project. Sampling is performed non-destructively by swabbing the parchment, followed by microbial DNA isolation, amplification, library preparation, sequencing, and data analysis (as described in Figure 1).
By comparing the microbiota of parchment manuscripts from various library collections within Germany and globally, the indigenous microbiota can be characterised. Storage conditions and provenance may indicate variations in microbial composition. Comparing decayed parchment sections with intact ones may help identify potential collagen degraders. These degraders will be further analysed, and their metabolic traits visualised through whole genome sequencing or transcriptome analysis.
The project is expected to provide detailed information about the microbiota and the factors influencing its composition. Potential decay-inducing organisms will be identified and tested in vitro on parchment. The results aim to emphasise the importance of individual conservation management of ancient manuscripts and to enhance understanding of the microbiological processes underlying parchment decay.