Underneath the Purple Stain

Abstract

The Alcobacenses are one of the most important Portuguese collections of Monastic codices. During a campaign study to further advance our knowledge on this important legacy and its state of conservation, a heavily deteriorated codex (ALC.338) stood out due to the presence of purple stains on the lower margins on virtually all folios. In some of them, the purple stains are accompanied by yellow and brown patches as well. Also noticed was the presence of these purple spots on the white tawed leather covering the codex. The codex was analyzed macro and microscopically, chemically and biologically using state-of-the-art technology such as next-generation sequencing. The biological deterioration associated with the appearance of these purple spots arises from the inside out and reveals significant abundance of the bacterial genus Saccharopolyspora sp., which accounted for 86% of the bacterial genera identified. For the fungal population, the most common genus was Malassezia sp. Visual inspection of the sample confirmed the presence of fungal and bacterial biofilms. Pressing questions, comparison to similar studies and future perspectives are also given.

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“…It is also found within other warm-blooded animals [77]. Although Malassezia is an unusual contaminant in cultural heritage, recent studies have revealed its unexpected presence on cultural heritage artifacts, such as ancient manuscripts, paintings, sculptures, photograph, and textiles [78,79]. The presence of this fungus on such objects poses new challenges for conservators and researchers due to its ability to degrade cellulose and produce lipolytic enzymes [80].…”

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“…At the same time, more marine bacteria begin to grow, feeding on the remains of archaea and the attacked collagen matrix. Gradually, more and more bacteria and fungi can colonise, causing the collagen to break down so that the manuscripts begin to disintegrate [ 24 , 147 ]. Another research group held Actinobacteria and Aspergillus species responsible for the appearance of the purple spots.…”

“…The smaller peptides obtained can then be analysed using mass spectrometers and assigned to the corresponding proteins with the help of matching to databases. The disadvantage of this approach is that complete sequence coverage can often not be achieved and that fragments with post-translational modifications (PTMs), protein truncations, as well as alternative splicing events cannot be identified [ 13 , 147 , 168 ]. In the top-down approach, intact proteins are analysed so that proteoforms can also be characterised.…”