Ötzis non-human DNA: Opportunistic pathogen discovered in Iceman tissue biopsy

Ötzi's human genome was decoded from a hip bone sample taken from the 5,300 year old mummy. However the tiny sample weighing no more than 0.1 g provides so much more information.

A team of scientists from EURAC in Bolzano/Bozen together with colleagues from the University of Vienna successfully analysed the non-human DNA in the sample. They found evidence for the presence of Treponema denticola, an opportunistic pathogen involved in the development of periodontal disease.

Thus, by just looking at the DNA, the researchers could support a CT-based diagnosis made last year which indicated that the Iceman suffered from periodontitis. The results of the current study have recently been published in the online scientific journal PLoS ONE.

Much of what we know about Ötzi -- for example what he looked like or that he suffered from lactose intolerance -- stems from a tiny bone sample which allowed the decoding of his genetic make-up. Now, however, the team of scientists have examined more closely the part of the sample consisting of non-human DNA. "What is new is that we did not carry out a directed DNA analysis but rather investigated the whole spectrum of DNA to better understand which organisms are in this sample and what is their potential function," is how Frank Maixner, from the EURAC Institute for Mummies and the Iceman in Bozen/Bolzano, described the new approach which the team of scientists are now pursuing.

"This 'non-human' DNA mostly derives from bacteria normally living on and within our body. Only the interplay between certain bacteria or an imbalance within this bacterial community might cause certain diseases. Therefore it is highly important to reconstruct and understand the bacterial community composition by analysing this DNA mixture," said Thomas Rattei, Professor of Bioinformatics from the Department of Microbiology and Ecosystem Science at the University of Vienna.