The microbiome of Da Vinci’s drawings

The work of Leonardo Da Vinci is a priceless heritage of the 15th century. From engineering to anatomy, the master paved the way for many scientific disciplines. But what else could Da Vinci’s drawings teach us? Could molecular studies reveal interesting data from the past? These questions led an interdisciplinary team of researchers, curators and bioinformaticians, from both the University of Natural Resources and Life Sciences and the Vienna University of Applied Sciences in Austria, as well as the Central Institute of Archives and Book Pathology (ICPAL ) in Italy, to collaborate and study the microbiome of seven different drawings by Leonardo Da Vinci.

Molecular study of works of art has already proved a valuable approach, and Dr. Piñar, the study’s first author, is not on her first attempt. In 2019 his team was able to investigate the conservation conditions and also the possible geographical origin of three statues confiscated from smugglers through the study of their microbiome and, earlier this year, the microbiome of ancient scrolls made it possible to clarify the animal origin of the skins used for their manufacture 1,000 years ago. In the study presented here, the Austrian team uses an innovative genomic approach called Nanopore, regarded as third-generation sequencing, to reveal the complete microbiome composition of many of Da Vinci’s designs for the first time. The study is published today in Frontiers in microbiology.

Overall, the results show a surprising predominance of bacteria over fungi. Until now, mushrooms were thought to be a dominant community in paper-supported art and tended to be the primary focus of microbial analysis due to their biodeterioration potential. Here a high percentage of these bacteria are either typical of the human microbiome, certainly introduced by the intensive manipulation of the drawings during the restoration work, or they correspond to insect microbiomes, which may have been introduced, long ago, through flies and their excrement.

A second interesting observation is the presence of a lot of human DNA. Unfortunately, we cannot assume that this DNA comes from the master himself, but it may rather have been introduced by restorers over the years. Finally, for both bacterial and fungal communities, the correlation with the geographic location of the drawings can be observed.

Overall, the insects, the restorers and the geographic location all seem to have left an invisible trace on the drawings. Although it is difficult to say whether any of these contaminants came from the time when Leonardo Da Vinci was drawing his drawings, Dr Piñar points out the importance that monitoring these data could have: “The sensitivity of the Nanopore sequencing method offers an excellent tool for monitoring objects of art. It allows the evaluation of microbiomes and the visualization of its variations due to harmful situations. It can be used as a bio-archive of the history of objects, providing a sort of digital footprint for current and future comparisons. ” , scientists could develop new methods not only to preserve the visual aspect of art, but also to document the invisible journey of our artistic and cultural heritage.