Scientists Found 5,300-Year-Old Viable Yeast in a Mummy’s Gut — and Baked Sourdough With It

• 5,300 years age of the viable yeast colonies found in Ötzi the Iceman's preserved gut — Microbiome journal · Eurac Research · June 2026
• 4 species cold-adapted yeasts identified: Glaciozyma, Phenoliferia, Goffeauzyma, Mrakia — none are common baker's yeast — Sarhan et al., 2026
• −6°C Ötzi's storage temperature at the South Tyrol Museum since 1998 — the same cold environment the yeasts continued slowly proliferating in — Eurac Research, Bolzano
• Sept. 19, 1991 date German hikers Helmut and Erika Simon discovered Ötzi's body frozen in Alpine ice at 3,210 m elevation — South Tyrol Museum of Archaeology

The yeast had been there for five millennia, locked inside the remains of a Copper Age man who died in the Alps. A research team at Eurac Research in Bolzano, Italy, extracted it, cultured it in a refrigerator, and baked a loaf of sourdough bread with it. Lead researcher Mohamed S. Sarhantook a bite. “We had a very, very good sourdough,” he said, laughing.

The discovery, published June 2–3, 2026 in the journal Microbiome, is not just a culinary curiosity. Sarhan and his co-authors found four species of viable cold-adapted yeast living on and inside Ötzi the Iceman, the world’s best-preserved ancient mummy — a man who walked the Ötztal Alps around 3300 BC, was killed by an arrowhead to the left shoulder, and spent the next 5,300 years frozen in glacial ice before two German hikers stumbled across his body in September 1991.

Some of those yeasts, they discovered, had adapted to metabolize the very chemical used to preserve him after his recovery. The same yeast that survived 53 centuries in a glacier — and then ate his preservative — made excellent bread.

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Ötzi the Iceman is Copper Age Europe’s most intimate document. He is not a skeleton or a burial artifact. He is, as Frank Maixner— director of Eurac Research’s Institute for Mummy Studies and co-author of the new study — put it: “not a static relic, but a dynamic biological system.”

Ötzi died at roughly 45 years old — brown-eyed, lactose-intolerant, predisposed to cardiovascular disease, carrying Lyme disease — somewhere around 3300 BC. His final hours were violent: he ate a last meal of ibex meat, red deer, einkorn wheat, and bracken fern, then was shot in the left shoulder by an arrow that lacerated a subclavian artery. He bled out in 30 to 60 minutes, at 3,210 meters of elevation on the ridge now separating Austria from Italy, and was buried by glacial ice.

When hikers Helmut and Erika Simon found him on September 19, 1991, he was so well-preserved that Austrian authorities first thought he was a modern hiking fatality. He was not. After radiometric dating confirmed his age, the mummy was transferred to the South Tyrol Museum of Archaeology in Bolzano, Italy, where he has been stored since 1998 at a constant −6°C in a custom cold cell. That cold cell, it turned out, was exactly the right environment for the microbes that had been riding along.

Researchers had long known Ötzi’s gut held scientific treasure. A 2016 study published the oldest-ever sequenced strain of Helicobacter pylori — a predominantly Asian strain, evidence that the African migration wave that introduced modern European H. pylori had not yet reached the Alps in his time. A 2018 Current Biology paper reconstructed his last meal: minimally heated ibex and red deer, with roughly 50% of the undigested food being fat by weight. His stomach, unexpectedly positioned high in the ribcage, was only identified at all during a 2010 CT scan.

But nobody had looked for living yeast. Nobody expected to find any.

Sarhan and his colleagues took samples from three sources: Ötzi’s skin surface, his stomach and gut tissue, and the brownish meltwater that had pooled around his partially thawed body during recovery. They compared sets taken in 2010 and again in 2019. Four yeast genera came back repeatedly: Glaciozyma, Phenoliferia, Goffeauzyma, and Mrakia.

None of these are Saccharomyces cerevisiae, the common baker’s and brewer’s yeast. All four are psychrophilic — cold-adapted — genera associated with Antarctic soil, alpine snowpacks, and glacial environments. They thrive at sub-zero temperatures. The museum’s −6°C storage had been their habitat all along.

Comparing the 2010 and 2019 sample sets, the team found that Glaciozyma had shifted from a minor species to the dominant one. The yeast was not merely surviving — it was, slowly, growing. Ancient DNA damage patterns in the recovered genomes confirmed these were not modern lab contaminants. They were ancient colonizers, and they had been there for a very long time.

“What we didn't expect to find was yeast.”

Mohamed S. Sarhan, lead researcher, Eurac Research Institute for Mummy Studies, June 2026

Sarhan told Live Science that the team believes the yeasts colonized Ötzi’s body after his death, from the glacial environment around him — not during his lifetime. They are not evidence that Ötzi personally brewed beer or baked sourdough. The cold-adapted genera are utterly different from the fermentation yeasts that Bronze Age and Neolithic agricultural societies used for bread and ale. But their survival across 53 centuries, and their continued viability under laboratory conditions, opened an unexpected door.

“If you tell anyone you have yeast,” Sarhan said, “they immediately ask: can we use it for bread?”

Sarhan cultured the recovered yeasts at refrigerator temperature, replicating the cold environment where they had thrived for millennia. Initial attempts at fermentation failed. The team persisted. After roughly three months, they achieved a successful sourdough starter and baked a loaf.

The tasting notes, as delivered by the lead researcher, were brief and enthusiastic. “We had a very, very good sourdough,” Sarhan said — the quote accompanied, in most interview accounts, by a laugh. No formal sensory panel or crumb-structure analysis has been published. The bread was good. That appears to be sufficient.

Beer is next. When asked whether brewing was on the agenda, Sarhan confirmed it was “on the list.” The cold-adapted yeasts, which operate at temperatures that would stall or kill common ale yeasts, could have industrial applications in low-temperature fermentation. That possibility, combined with a separate finding about their chemistry, makes this study considerably more than a party trick.

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After Ötzi’s recovery in 1991, conservators applied phenol — a disinfectant and fungicide — to his surface to prevent further microbial growth. They did not anticipate that certain residents of that surface could eat it.

Three of the four recovered yeast species carry the genetic capacity to metabolize phenol as a carbon source. They had adapted, over their long residence on the mummy, to consume the very chemical that was supposed to eliminate them. The researchers noted this was not just an evolutionary curiosity. Cold-adapted, phenol-metabolizing yeasts could have practical applications in bioremediation — breaking down phenol-contaminated industrial waste or soil at low temperatures where conventional microbes would be inactive.

The study also identified a third microbial layer — one less romantic than ancient yeast, but scientifically important. UV-treated spray water applied to Ötzi’s skin to prevent moisture loss had introduced modern environmental bacteria. The paper distinguishes three overlapping communities: the original Copper Age gut flora from his lifetime, the post-mortem glacial colonizers (including the bread-capable yeast), and the more recent conservation-introduced microbes. Maixner described the mummy not as a frozen time capsule but as “a living biological interface — a meeting point between the ancient world and the present.”

The 2026 yeast study is the latest chapter in a decades-long scientific reading of Ötzi’s digestive tract. It has yielded more concentrated revelations per square centimeter of tissue than almost any archaeological find in history.

In 2016, researchers published the oldest-ever sequenced Helicobacter pylori strain recovered from the mummy’s stomach. The strain was predominantly South Asian rather than the African-European hybrid seen in modern Europeans — confirming that the African migration wave bringing the common European H. pylori type had not yet reached the Alpine population by 3300 BC. Ötzi had been infected with H. pylori his entire life and apparently felt fine, consistent with pre-modern exposure norms.

In 2018, a Current Biology paper reconstructed his last meal with unusual precision: air-dried ibex meat, red deer, einkorn wheat, and traces of bracken fern — the bracken consistent with medicinal use, as it has mild antiparasitic properties, and Ötzi was known to carry whipworm (Trichuris trichiura). Roughly half the undigested contents were fat by weight. He had eaten 30 to 60 minutes before he was killed. His stomach — only identified during a 2010 CT scan, unexpectedly positioned high in the ribcage — was so intact that researchers could reconstruct the texture of what he had chewed.

“We see continuity here. These yeasts have accompanied Ötzi on his long journey through the millennia.”

Frank Maixner, Director, Institute for Mummy Studies, Eurac Research, June 2026

Sarhan listed three near-term research directions: brewing (the yeast performs best in cold conditions that would be prohibitive for conventional ale fermentation, opening potential for a distinctive style of cold-fermented beer), industrial bioremediation (the phenol-metabolizing capacity, combined with cold-tolerance, could be useful in contaminated-soil remediation at temperatures where most microbes are dormant), and continued paleomicrobiome research using the study’s methodology on other permafrost-preserved or glacially-mummified specimens.

The paper also has a methodological implication for museum conservation. The discovery that modern spray-water and phenol applications leave detectable microbial signatures in preserved remains means future researchers will need to account for those layers when interpreting ancient microbiome data. Ötzi, who has been in scientific custody for 35 years, now carries at least three distinct microbial eras within him — his own lifetime, the glacier, and the museum.

The Eurac Research team plans to continue annual monitoring. The yeasts are not going anywhere. They have demonstrated, at minimum, that they can outlast empires.

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