Meet the microbes that live on Da Vinci’s iconic sketches

“Of course, we found a lot of bacteria related to the skin microbiome,” says Piñar. “So when you touch it, you leave your microbiome there.” You might be thinking: So does this mean that we now know what was crawling on Da Vinci’s hands when he was drawing these masterpieces? Unfortunately not, as the drawings have been handled by many, many other people in the five centuries since the master sketched them. And to be clear, this genetic sequencing didn’t tell the researchers whether all these bacteria were alive or dead, just that they were present in some form.

Among the microbes in human skin, the researchers found high levels of the genus of bacteria Moraxella, particularly Moraxella osloensis, responsible for the stench of dirty laundry. Additionally, they detected the infamous bacteria Salmonella is E. coli., both of which lead to turmoil in the human intestine. They also found species of bacteria specific to the guts of common flies and fruit flies, meaning the insects brazenly defecated on priceless works of art, at least until someone put them in perfectly clean drawers for storage. , or behind the glass where they appear. , sealed and stored at the perfect temperature and humidity. “Since the drawings are preserved today, there’s no way the bugs can get in and, you know, do their thing there,” says Piñar. “It is no longer possible. So you have to think this could be from the times when the designs weren’t archived as they are now. “

Piñar and his colleagues also found Aspergillus, a mold dangerous for some people to inhale and has detected species of the genus Penicillium, the fungus that gave us penicillin. Most troubling to both the works of art and the conservators who manage them, the analysis uncovered the fungus Alternaria, known as a “card spoiler” for its habit of … spoiling the card. It is also an allergen that can be dangerous if inhaled.

The team also found the fungi responsible for the paper ‘foxing’ – the yellow-brown spots that have formed over the years. In addition to DNA analysis, the researchers sifted the surface of the drawings with a microscope and found encrustations of calcium oxalate crystals produced by these fungi. “So you can deduce a lot from this microscopic analysis and complete the molecular analysis we do here very well,” says Piñar.