Ötzi’s icy microbes are still metabolically active

Ötzi’s microbiome – A new study suggests the microbial community linked to Ötzi the Iceman—preserved for more than 5,300 years in the Italian Alps—may still show signs of activity, including yeast strains adapted to extreme cold. Researchers warn that even the conditions used to

For more than 5,300 years, Ötzi the Iceman has been locked inside ice and history. Researchers have now turned their attention to something more restless than the corpse itself: the microbes associated with his body.

They report in the journal *Microbiome* that yeast strains—some adapted to extreme cold—may still be metabolically active. The work centers on Ötzi’s remains from the glacial area of the Italian Alps. where cold temperatures and relatively low oxygen helped preserve his body in a way that effectively mummified it for millennia.

Since Ötzi was discovered, his conservation has relied on tight environmental control. His body has been kept in a refrigerated chamber at minus six degrees Celsius (21.2 degrees Fahrenheit) with high humidity designed to keep the mummy intact. The conditions before and after discovery appear to have done something rare: genetic fragments from microbes living in Ötzi’s gut survived as well.

“**This combination preserved the DNA of the mummy and also the DNA of the bacteria, the indigenous microbiome, but also the environmental DNA surrounding the mummy,**” said Mohamed Sarhan, a microbiologist at Italy’s Eurac Research Institute for Mummy Studies and lead author of the new paper.

Sarhan and his team did more than read the genetic remnants. They analyzed the microbial and fungal populations on Ötzi’s skin. various tissues. and thawed water collected from inside the mummy. Among what they found were multiple species of anaerobic bacteria—including **Romboutsia hominis. Clostridium moniliforme. Ruminococcus bromii**. and others—bacteria researchers say would have helped Ötzi digest his food.

A previous analysis of Ötzi’s stomach and microbiome had suggested his diet was high in fat and included dried wild meat and cereals. along with a poisonous fern. Sarhan said the microbial species identified in the mummy largely match that diet because they are suited to thrive on those foods. Some of those species can still be found in the intestines of modern-day humans, he said. Others, however, are far less common today as diets have shifted.

“We have two or three species that were never reported before in [Ötzi’s] case that we know already are very rarely found in modern humans. ” Sarhan said. “We can still find them in some nonindustrialized societies. like some tribes in Africa or South America and also some places in Europe. but in very. very rare cases.”.

Yeast adds a second, more complicated story. Samples of yeast taken from Ötzi’s skin and stomach—and from meltwater that had seeped into the body—revealed several cold-adapted species. Researchers interpret that as evidence these microbes originated in the environment where Ötzi was found.

But when the team compared these yeast samples to others taken **nine years earlier**, they found the yeast populations had changed. Species able to digest **phenol**, a chemical used to disinfect the Iceman, had grown—even with the below-freezing temperatures used to keep the body.

Sarhan said the finding could matter for how the mummy is conserved.

“This needs to be to be followed up on in the future to understand what happened during this time and also what will happen in the future. ” he said. “How we can stop this…?. One of the things that we don’t want to forget is that the conservation of the Iceman includes everything: the Iceman as a body but also the biomolecules. proteins. DNA. metabolites and also the internal bacteria.”.

The implications are practical as well as scientific. Sarhan argues the knowledge could help caretakers keep the body well preserved into the future and help other researchers reproduce similar work on other frozen biological discoveries.

“The main motivation of this study was the microbiological conservation of the mummy,” Sarhan said. “We wanted to understand whether the current conditions of the preservation are good enough.”

Sarhan also expects more discoveries as sequencing and bacterial cultivation technology improves. Still, the central mystery of Ötzi’s death—how exactly he died—may remain a cold case.

In the meantime, the message from inside the ice is clear: even when everything appears frozen in time, the smallest living remnants can still make their presence felt.

Ötzi the Iceman microbiome ancient microbes yeast cold-adapted species anaerobic bacteria Eurac Research Institute Microbiome journal mummy preservation phenol microbial DNA