Much of what we know about Öetzi - the 'Tyrolean Iceman’ – such as what he looked like and that he suffered from lactose intolerance, stems from a tiny bone sample which allowed the decoding of his genetic make-up.
A team of scientists have examined the part of the sample consisting of non-human DNA. In the DNA mixture, they detected a sizeable presence of a particular bacterium: Treponema denticola, an opportunistic pathogen involved in the development of periodontitis. The finding supports the computer tomography based diagnosis that the Iceman suffered from periodontitis.
What is also surprising is that the analysis of a tiny bone sample can still, after 5,300 years, provide information that the pathogen seems to have been distributed via the bloodstream from the mouth to the hip bone. Furthermore, the investigations indicate that these members of the human commensal oral microflora were old bacteria which did not colonize the body after death.
"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 .
"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.
Besides the opportunistic pathogen, the team of scientists led by Albert Zink, head of the EURAC Institute for Mummies and the Iceman, also detected Clostridia-like bacteria in the Iceman bone sample which are at present most presumably in a kind of dormant state. Under hermetically sealed, anaerobic conditions, however, these bacteria can re-grow and degrade tissue.
This discovery may well play a significant part in the future conservation of the world-famous mummy.
"This finding indicates that altered conditions for preserving the glacier mummy, for example when changing to a nitrogen-based atmosphere commonly used for objects of cultural value, will require additional micro-biological monitoring," they explained.
Now it's time to look closer at the microbiome of the Iceman.