Research press release


Scientific Reports

Microbiology: Deep purple damage to an ancient scroll

13世紀の羊皮紙の巻物に生じた紫色のシミの原因微生物が見つかったことを報告するLuciana Miglioreたちの論文が、今週掲載される。古い羊皮紙文書は微生物に侵されることが多く、その結果として紫色のシミが生じ、羊皮紙の表層がはがれて、文書の可読性が損なわれる。Miglioreたちは、今回の研究で得た新知見が古い羊皮紙文書の修復と保全に役立てられることを期待している。

A. A. Arm. I-XVIII 3328は、西暦1244年に列聖調査のために作成された長さ5 mの羊皮紙文書で、男を誤って殺してしまったLaurentius Loricatusという名の若い兵士の話が記されている(列聖とは、信仰心の厚い教徒などを聖人として認定すること)。この兵士は、罪を償うため、その後34年間にわたってスビアコ(イタリア)近くの洞窟に引きこもった。ところが、この羊皮紙文書は紫色のシミに覆いつくされ、羊皮紙のコラーゲン構造が損傷し、文書の可読性が著しく損なわれている。この羊皮紙の損傷は、この巻物が18世紀末にバチカン秘密文書館に移される前に生じた可能性が非常に高い。現在、この巻物は、管理された環境条件下で保管されている。


The microorganisms responsible for purple spots on a 13th century scroll have been identified in a study in Scientific Reports. Ancient parchments are commonly attacked by microbes, resulting in purple spots and the detachment of the superficial layer of the document, which affects the readability. The authors hope that their findings may help in the restoration and conservation of ancient parchments.

The five-metre long parchment, A.A. Arm. I-XVIII 3328, written in 1244 AD for a canonization inquiry, tells the story of a young soldier called Laurentius Loricatus who killed a man by accident. To make amends for his crime, he retired to a cave near Subiaco, Italy, for the next 34 years. However, the document is covered in purple spots, with damage to the collagen structure significantly affecting its readability. The damage is most likely to have occurred prior to the scroll being moved to the Vatican Secret Archive at the end of the 18th century, where it is now kept under controlled environmental conditions.

By performing a genetic analysis of the microbial communities colonizing the scroll, Luciana Migliore and colleagues found that Gammaproteobacteria were present in the purple spots but absent in the undamaged areas of the parchment. The authors suggest that deterioration of the parchment occurred during a process of microbial succession, in which Halobacteria - responsible for the rhodopsins that produce the purple spots - were replaced by Gammaproteobacteria, only leaving the purple stains behind. The authors suggest that further studies could help identify the exact sequence of microbes that produced the rhodopsins responsible for the spots and may reveal new approaches to aid in the restoration of documents damaged in this manner.

doi: 10.1038/s41598-017-05398-7


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