Unexpected Microbes on Ötzi the Iceman’s 5,300-Year-Old Body May Have Fed on Chemicals Used to Preserve Him

Ötzi the Iceman has spent more than 30 years in a climate-controlled chamber in a museum in Bolzano, Italy, kept at about 20 degrees Fahrenheit (negative 6 degrees Celsius) to stop time from touching him. It has worked, mostly.

A new study published in the journal Microbiome found cold-loving yeasts on his body that appear to have been with him since his time in the glacier and may still be surviving today. It also found traces of gut bacteria that have largely vanished from modern human guts. Ötzi, it turns out, has not been alone, and what remains with him may tell us something about the microbial world humans have lost.

“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,” said microbiologist and lead author Mohamed S. Sarhan in a press release.

Ötzi the Iceman’s Cold-Loving Yeasts May Still Be Surviving

There was one detail the researchers did not expect. After Ötzi’s recovery in 1991, conservators applied a chemical treatment to his surface to clear fungal growth. Three of the four yeast species found in the new study carry genes that allow them to break down that same chemical.

The implication is uncomfortable, as efforts to protect the mummy may have inadvertently given certain microorganisms something to eat.

“These yeasts have accompanied Ötzi on his long journey through the millennia,” explained Frank Maixner, director of the Institute for Mummy Studies at Eurac Research. This shows that the mummy is “not a static relic, but a dynamic biological system.”

Read More: Fragments of Homer’s Iliad Found Buried with Roman-Era Mummy

How They Know the Yeasts May Still Be There

The yeasts were found in samples taken from Ötzi’s skin, meltwater collected inside the mummy, and his stomach contents. The team also analyzed ice from the glacier’s surface and a soil sample collected and frozen at the discovery site during Ötzi’s recovery.

Genetic analysis placed the yeasts among cold-adapted species with relatives in some of the harshest environments on Earth, including Antarctica, pointing to a glacial origin.

Their genetic material helped separate them from ordinary contamination. Microbes that died long ago tend to leave behind badly degraded DNA. But the yeasts showed a mix of damaged ancient DNA and well-preserved modern DNA. That combination points to how they are not simply frozen leftovers from the glacier. Some may still be surviving under the museum’s current preservation conditions, possibly in a dormant state.

The team also had to separate Ötzi’s own ancient microbes from later hitchhikers picked up in the ice or after his recovery.

A Biological Record Most of Us No Longer Carry

Inside the mummy, the team also found traces of bacteria from Ötzi’s original gut. First described in a 2019 study, that microbial community resembles the few known examples of gut flora from early human populations. Some of those bacteria are now rare in people living in industrialized societies, a shift likely tied to changes in diet, sanitation, antibiotics, and environment over thousands of years.

Those same cold-loving traits may have uses outside archaeology. In theory, microbes that work in the cold could help run processes such as fermentation with less heat and less energy.

For Ötzi’s caretakers, the study is a reminder that preserving a mummy also means monitoring the tiny organisms that may still live with it.

Ötzi has been studied for more than three decades. It turns out parts of the world he carried with him into the glacier are still here too.

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• This article references information from a study published in Microbiome: The Iceman’s microbiome: unveiling millennia of microbial diversity and continuity