Purple Spots Marring Vatican Scroll Have Unlikely Source

Call it the attack of the purple pigment. Live Science reports purple splotches are damaging old animal-skin parchments around the world. Take, for example, a 16-foot-long scroll inside the Vatican Secret Archives. The parchment was written by Italian villagers in 1244 asking the Church to make Laurentius Loricatus a saint. Loricatus was a teenage soldier who, having accidentally killed a man, spent the next 34 years in a cave burning his face with a hot iron and otherwise punishing himself to atone for his sins. While the story of Loricatus is interesting, it's incomplete thanks to those damned purple spots. Purple pigment dots the scroll's margins and completely obscures the first and last pages. But thanks to a study published Thursday in Scientific Reports, we may finally know why so many old parchments look like Prince.

Scientists subjected flakes of the Loricatus scroll to new genetic sequencing techniques, and lead researcher Luciana Migliore says the results were "absolutely surprising," Gizmodo reports. The purple spots were being caused by Halobacteria, a type of marine microbe that eats salt, according to AFP. Not the kind of thing you'd expect to find on a goat-skin parchment nowhere near the ocean, Migliore recalls her initial reaction: "There must be some mistake." The explanation lies in the process used to create parchments worldwide: The animal skin is first soaked in a sea-salt bath to preserve it by killing flesh-eating bacteria. That, however, introduces the salt-eating bacteria, which create purple pigments. Migliore and her team are looking into ways to possibly remove the purple splotches. (Scientists virtually unrolled a scroll turned to charcoal in a fire.)