Scientists mapped Ötzi the Iceman’s microbiome and found living fungi from the Copper Age

Five thousand three hundred years after Ötzi died in the Alps, something on his skin is still alive. A new study published in Microbiome by Mohamed S. Sarhan and colleagues at Eurac Research has reconstructed 38 bacterial and 5 fungal genomes from the world's most famous mummy, and cultured four living psychrophilic (cold-adapted) yeast strains from his tissues. Some of those yeasts show ancient DNA damage patterns suggesting they are either dormant survivors or direct descendants of microbes that colonized Ötzi during his Copper Age lifetime.

Four living yeasts cultured from Ötzi's 5,300-year-old skin

The four yeast strains, Glaciozyma watsonii, Mrakia robertii, Phenoliferia glacialis, and Goffeauzyma sp., were not simply detected by sequencing: the team grew them in the laboratory. All four can thrive at -6°C and 99% relative humidity, conditions that match Ötzi's refrigeration chamber at the South Tyrol Museum of Archaeology almost exactly. That overlap between preservation environment and microbial habitat is not coincidental; these organisms are genuinely at home on the mummy.

Between 2010 and 2019, Glaciozyma shifted from a minor presence to the dominant yeast strain on Ötzi's skin, a sign of active proliferation rather than passive contamination. Similar cold-adapted yeasts are found in Alpine cryoconite, Antarctic sediments, and Greenland ice, placing Ötzi's microbial passengers within a broader ecology of extreme environments. Earlier genomic work on Ötzi's ancient gut microbiota had already catalogued a rich bacterial community, including Clostridium and Pseudomonas species, but the fungal layer had never been cultured live before.

As Sarhan put it: "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."

What a Copper Age microbiome reveals about microbial evolution

Ötzi's frozen body functions as what the authors call a "biological time capsule." His stomach already yielded Helicobacter pylori in previous research, a strain closer to an Asian lineage than the modern European hybrid, a finding that reshaped thinking about human migration patterns. His intestines contained bread, vegetables, and venison, confirming a varied Copper Age diet.

The new study layers fungal and bacterial genomics onto that picture. Ancient microbiome research more broadly has shown that ancestral gut communities differ sharply from modern ones, with industrialization apparently driving losses in microbial diversity linked to metabolic and immune diseases. Work on ancient North American populations has connected microbiome shifts to conditions like diabetes, suggesting that studying pre-industrial microbiomes is not mere historical curiosity but a way to understand what a healthy baseline might look like. Ötzi's mummy offers a datable, well-preserved anchor point in that longer story.

Frank Maixner, a co-author, framed it this way: "The Iceman is not a static relic, but a dynamic biological system."

How shotgun metagenomics and live culture separated ancient from modern microbes

Disentangling Copper Age colonizers from microbes introduced after Ötzi's 1991 discovery required layered methods. Samples came from skin, stomach tissue, and thawed melt water from the mummy's interior. The team reconstructed genomes using deep sequencing and then checked each organism for ancient DNA damage signatures, the characteristic misreading errors that accumulate in degraded genetic material over centuries. Organisms showing those damage patterns are plausible ancient residents; clean genomes flag modern introductions. The case for shotgun metagenomics over older amplification methods in ancient microbiome work has been building for years, and this study leans fully into that approach, allowing the team to reconstruct complete or near-complete genomes rather than short marker sequences.

Modern contaminants were also traced to a practical source: the humidity-control spray water used to keep the mummy from drying out. Some modern bacterial genomes matched organisms typical of such water systems, providing a mundane explanation for their presence.

Phenol treatment and collagenase genes raise preservation questions

One of the study's more unsettling findings concerns the mummy's own preservation history. After Ötzi's discovery, conservators applied a phenol solution to prevent mold growth. That treatment inadvertently selected for phenol-degrading microbes: three of the four cultured yeast strains and a bacterium, Pseudomonas sp. 5C2, carry genes for breaking down phenol. A human intervention meant to protect the mummy may have handed a competitive advantage to exactly the microbial types capable of processing its chemicals.

More concerning still, Clostridium algidicarnis in the bacterial fraction carries collagenase genes, enzymes capable of breaking down collagen, the structural protein that holds tissue together. Other microbes in the community encode proteases and lipases. No observed tissue damage has been reported so far, and westernization-driven microbiome disruption research reminds us that microbial potential and actual activity are different things. But the presence of those degradative gene sets is enough that Sarhan and colleagues recommend shifting from occasional monitoring to periodic genomic surveillance of the mummy's microbial community.

Periodic genomic surveillance and an unexpected bread experiment

The study's practical recommendations are cautious and specific. The authors are not calling for alarm; no deterioration has been observed. But they argue that a mummy as scientifically irreplaceable as Ötzi deserves a more systematic watch over its microbial residents, with regular sequencing to catch any shift in community composition before damage occurs.

On the more playful end of the findings: one of the cultured yeast strains successfully fermented dough. Sarhan's two-word assessment, "It works," is buried in the paper as a scientific observation rather than a product pitch. The authors are careful to note that cold-adapted Glaciozyma strains are unlikely to displace the industrial workhorse Saccharomyces cerevisiae in commercial baking anytime soon. The fermentation result is a proof of biological activity, not a recipe. What it confirms is that at least one organism from a 5,300-year-old mummy retains enough metabolic vigor to do something a modern baker would recognize.