Researchers from the University of Natural Resources and Life Sciences, the University of Applied Science of Wien and the Central Institute for Pathology of Archives and Books (ICPAL) studied seven drawings by Leonardo Da Vinci for their microbiome.

Sampling microbes from da Vinci's Portrait of a Man in Red Chalk (1512) Source: University of Natural Resources and Life Science/University of Applied Science of Wien in Austria/Central Institute for the Pathology of Archives and Books

In their study, the team used a genomic approach called Nanopore, which is considered third-generation sequencing. Nanopore used genetic sequencing to reveal the complete microbiome composition of the Da Vinci drawings.

The team discovered that there was a dominance of bacteria over fungi on the drawings. It was previously believed that fungi were the dominant community living in paper-based art. Because of this, fungi have been the main focus of previous microbial analysis.

A high proportion of bacteria is typical of the human microbiome. Bacteria are introduced to the drawings during the intensive handling that happens during restoration. The bacteria levels also correspond with insect microbiomes that were introduced a long time ago through flies and their excrement. The second discovery they made was the presence of human DNA. While this is exciting, the team said they do not assume that the DNA came from Da Vinci. It is more likely that it came from the various restoration processes the drawings have been through over the years.

The bacterial and fungal communities on the drawings had a correlation with the drawing’s geographical location. Insects, restoration workers and geographical localization all leave tiny traces on the drawings.

This data is important because the sequencing method could be a good tool to monitor objects of art. It could also be used as a bio-archive of the object’s history and a fingerprint to be used with current and future comparisons. The team said their work could be used to create new methods to conserve art and document the invisible journey of artistic and cultural heritage.

The molecular study of art pieces holds a lot of valuable information. In 2019, researchers studied the storage conditions and possible geographical origin of three statues recovered from smugglers using microbiome study. In 2020, the microbiome of ancient parchments helped the team find the animal origin of skins used to manufacture the parchment thousands of years ago.

A paper on the research was published in Frontiers in Microbiology.