Some ancient microbes frozen with Ötzi the Iceman are still growing

Please don’t lick the science

What’s the difference between a person, an artifact, and an ecosystem?

Sarhan holds up a Petri dish of yeast cultured from Ötzi's stomach.

Credit:

Sarhan et al. 2026

Ötzi the Iceman, Europe’s most famous mummy, is crawling with microbes, some long dead, some still eking out a living after thousands of years, and some very modern.

After he died in the Ötztal Alps, the Copper Age man now known as Ötzi lay alone and forgotten for 5,300 years, until a group of hikers stumbled on his freeze-dried remains in 1991. Since then, he’s received a lot of attention from scientists, who have sequenced his DNA, pored over his last meal and the remains of his gut microbes, and examined his clothes and his broken tools. Today, Ötzi lies in a high-tech resting place at the South Tyrol Museum of Archaeology in Italy, where, it turns out, his body is still home to a handful of cold-adapted yeast species that have probably been with him since just after he died.

Slightly morbid souvenirs from the Alps

Microbiologist Mohamed S. Sarhan (of the Institute of Mummy Studies at the private Eurac Research center) and his colleagues recently sampled material from Ötzi’s stomach and meltwater from inside his body, swabbed his skin, and even sampled airborne microbes from his frozen storage room and the lab outside it. They also took samples from a block of frozen alpine soil taken from next to Ötzi’s body back in 1991.

We already know quite a bit about Ötzi’s gut microbes thanks to a 2019 study, but Sarhan and his colleagues wanted the bigger picture. Instead of just sequencing all the microbial DNA they could find on Ötzi, the researchers wanted to understand which species were really part of his ancient one-man ecosystem and which were modern contaminants.

Sarhan and his colleagues cultured some of the samples, and also put some through a process called shotgun metagenomics, which involves sequencing all the bits of DNA floating around in a sample. Inside Ötzi’s guts, Sarhan and his colleagues—like previous studies—found ancient DNA from a host of bacteria that match what we expect of ancient, “non-Westernized” gut microbiomes. But elsewhere on and in the mummy, the team also found some microbes that weren’t actually dead.

Ötzi is kept in carefully maintained conditions, as close as possible to the glacier that preserved his body for more than 5,000 years. The chamber is a brisk -6º Celsius, with 99 percent humidity carefully maintained by a spray of UV-treated water. That’s enough to protect the mummy from most of the microbes that usually help decompose human remains. But Sarhan and his colleagues were surprised to find that it’s also the perfect environment for a few microbes that Ötzi carried with him down from the mountains.

In samples from the mummy, Sarhan and his colleagues found four strains of cold-tolerant yeasts, all closely related to similar yeasts found in Arctic glaciers, in Antarctica, and high in the mountains of Italy and Russia. And unlike Ötzi’s long-dead gut bacteria, which left just broken, aging fragments of DNA behind, the yeasts seem to be alive and reproducing (albeit at, ahem, a glacial pace).

“These yeasts have accompanied Ötzi on his long journey through the millennia,” said Frank Maxiner, director of the Institute for Mummy Studies at Eurac and a coauthor of the recent study, in a press release. (Ötzi probably doesn’t find that terribly comforting, but you never know.)

Thawed ancient microbes or a long-lived colony?

The yeasts—species of Phenolifera, Glaciozyma, Goffeauzyma, and Mrakia, for the mycology fans—turned up on Ötzi’s skin, in his stomach, and in water sampled from inside his body. Sarhan and his colleagues cultured live yeast from the samples, but their shotgun metagenomics results also revealed a bunch of short fragments of DNA, most bearing the kind of damage that happens when DNA molecules break down over time. That’s a hallmark of ancient DNA, which meant that the yeasts had most likely been living on and in Ötzi’s body since shortly after he died.

And when Sarhan and his colleagues compared samples taken in 2010 to those taken in 2019, they saw longer fragments and less damage, on average—in other words, there was more recent DNA in the mix, which suggested the yeasts were slowly but persistently growing.

Yeasts like Glaciozyma have been found in small depressions in the glacial ice not far from where Ötzi’s body lay, so it makes sense that they’d have been among the microorganisms drawn to a fresh food source in the form of a dead Copper Age mountaineer. Or, as Sarhan and his colleagues put it, “potential postmortem infiltration through the mummy’s natural openings.” It’s the circle of life.

From there, the yeasts probably lay dormant in between brief thawing sessions, when they proliferated in transient patches of meltwater or moist tissue. And the yeasts may have actually gotten some help from modern efforts to preserve Ötzi’s remains. Three out of the four species can break down phenol, an antifungal compound that conservators used to treat the mummy in 1991. The treatment would have given those particular species an evolutionary edge over others.

“The central question that imposes itself now is whether these yeasts are descendants of ancient yeasts that maintained their multiplication along the years, or they were in a dormant state that was revived after thawing the mummy,” wrote Sarhan and his colleagues.

The researchers did reportedly make sourdough using cultures of at least one of the yeast species they identified on Ötzi, but they almost certainly didn’t use actual cultures taken from the mummy—for a mix of ethical, health, and practical reasons, ranging from “Eww!” to “Please don’t eat valuable scientific research material.” Having identified the species, it would have been easy to culture the same yeast from a starter that had, hopefully, never developed a taste for human flesh.

Life, uh, finds a way

Sarhan and his colleagues also found traces of a soil bacterium called Pseudomonas, which has probably also been with Ötzi at least since death, in nearly all of the samples from the mummy, as well as the soil taken from near his body on the glacier. And like the yeast, the bacteria seem to still be alive, in the slow way of organisms that live in the cold.

They’re even still evolving; the bacteria from Ötzi’s body have some small but noticeable genetic differences from the bacteria in the soil where he died, although they’re clearly related. It looks as if Pseudomonas colonized Ötzi’s body once and then, as Sarhan and his colleagues put it, “this specific strain may have adapted to the unique conditions of the conservation facility or the mummy’s tissues themselves.”

Meanwhile, in swabs from the mummy’s skin, Sarhan and his colleagues found bacteria like Methylobaderium and Sphingomonas, both known for being resilient in tough environments and for forming biofilms. Those species are currently a huge part of the microbiome on Ötzi’s skin, but not inside his body. Sarhan and his colleagues say they’re probably there thanks to the constant spray of UV-treated water that maintains the humidity in the conservation chamber.

“These taxa… have effectively reshaped the mummy’s external microbiome,” wrote Sarhan and his colleagues.

Not an artifact, but a “living archive” of microbes

Elisabeth Vallazza, the Director of the South Tyrol Museum of Archaeology that houses Ötzi, said in a press release that Ötzi is stable and he’s carefully monitored, adding that “further research and full conservation efforts are certainly needed to preserve it for many more generations.”

We can think of Ötzi’s microbiome in three parts: the microbes that lived in and on his body while he was running for his life through the Alps (like Rombousta hominsis and Clostridium moniliforme), the ones that moved in after his death (like Pseudomonas and the yeasts—which is also a great band name), and the ones that came from the environment he now rests in (like Methylobacterium). Five thousand years after his death, Ötzi’s body is still a whole ecosystem, built on the ruins of the one that once inhabited his body along with him.

“The Iceman is not a static relic, but a dynamic biological interface,” wrote Sarhan and his colleagues. And that’s the great truth of existence: life’s short, then you die—and the whole time, you’re a dynamic biological interface.

Microbiome, 2026. DOI: 10.1186/s40168-026-02417-6  (About DOIs).

Kiona is a freelance science journalist and resident archaeology nerd at Ars Technica.

7 Comments