Researchers used multiple sampling techniques to determine which microorganisms lived inside Ötzi during his lifetime and which arrived after his death. The later microbes could have colonized the body while it remained frozen in the glacier or during more than 30 years of modern conservation.
Genetic material recovered from internal tissues included bacteria that were part of Ötzi’s original gut flora. The team also made an unexpected discovery: cold-adapted yeast species that likely came from the glacier and have remained on the mummy into the present day. These organisms may eventually prove useful in industrial processes.
The findings were published in the journal Microbiome.
Tracing Ötzi’s Ancient and Modern Microbes
The investigation included a wide range of samples. Researchers studied ice collected from the mummy’s surface, meltwater from inside the body, and material gathered with numerous swabs. They also used previously available data from intestinal tissue and stomach contents.
To identify possible environmental sources, the scientists examined a soil sample taken from the discovery site during Ötzi’s recovery in 1991. The sample had remained frozen since it was collected.
Researchers found genetic evidence of Ötzi’s original gut microbiome in both his intestinal tract and stomach contents. This microbial community was first documented in a 2019 study conducted with Eurac Research.
Ötzi’s gut flora closely resembles the limited number of known microbiomes from early human populations. Many of these bacteria are rarely found in people living in modern industrialized societies. As a result, the mummy provides an unusual window into the microbial communities that once inhabited the human body.
Cold-Adapted Yeasts From the Glacier
The newly identified yeasts came from skin samples, meltwater inside the mummy, and stomach content samples. These highly specialized organisms are adapted to survive in cold environments.
Genetic testing showed that the yeasts are related to strains found in extremely cold places, including Antarctica. This connection supports the idea that they originated in the glacier and may have remained associated with Ötzi for thousands of years.
The scientists detected both heavily degraded (ancient) and well-preserved (modern) DNA. This combination suggests that the microorganisms are not simply biological remains from the distant past. They continue to exist under the mummy’s current storage conditions, which include a temperature of minus six degrees Celsius and high humidity. Some may be surviving in a dormant state.
“We see continuity here,” explains Frank Maixner, director of the Institute for Mummy Studies at Eurac Research: “These yeasts have accompanied Ötzi on his long journey through the millennia.”
According to Maixner, the results show that the mummy is “not a static relic, but a dynamic biological system.”
Past Conservation May Have Fed Some Yeasts
Earlier preservation treatments may have accidentally created favorable conditions for certain microorganisms. Three of the four yeast species have the genetic ability to break down phenol.
Phenol was used after Ötzi’s recovery to remove fungal growth from the surface of the mummy. The yeasts may have been capable of using the substance as a source of food.
“A mummy’s microbiome is unique because we are dealing with microbes that are over 5,000 years old and, at the same time, with modern microbes that have been introduced since the discovery,” says microbiologist and lead author Mohamed S. Sarhan.
Protecting Ötzi for Future Generations
The South Tyrol Museum of Archaeology oversees the preservation of the mummy and continuously monitors its condition.
“The mummy’s conservation conditions are very stable today,” comments Elisabeth Vallazza, director of the South Tyrol Museum of Archaeology that oversees the mummy’s conservation, “close microbiological monitoring ensures that the mummy suffers no damage. But further research and full conservation efforts are certainly needed to preserve it for many more generations.”
Scientists still do not completely understand how glacial mummies remain preserved over such long periods.
Conservation expert and co-author Marco Samadelli emphasizes: “The conditions under which glacial mummies are preserved are not yet fully understood. This study expands our knowledge in this area.”
Potential Uses in Low Temperature Industry
The research could contribute to improved methods for preserving Ötzi and other ancient remains. It may also lead to practical applications beyond archaeology.
Cold-adapted microorganisms can function at temperatures that would slow or stop many other species. They could therefore support industrial processes that require less energy, including fermentation performed at low temperatures.