Here’s what you’ll learn when reading this story:

• In a new study analyzing the microbiome of Ötzi the Iceman—arguably the most famous mummy ever discovered—scientists discovered four ancient cold-adapted yeast species.
• The researchers differentiated these species by reconstructing their genetics, showing that Ötzi remains a “dynamic biological interface” 5,300 years after his death.
• Using these cold-adapted yeasts, scientists investigated ways to make a sourdough starter that didn’t require additional heat for fermentation.

Few examples of human remains have provided such a detailed window into the past as Ötzi the Iceman. Discovered in 1991 along the border of Austria and Italy, Ötzi is the oldest mummy ever found in Europe and has taught scientists a great deal about Copper Age weaponry, the overall diet of high-altitude hunters (a high-fat mix of deer, goat, and grains), and even the cultural importance of tattoos (Ötzi had 61).

Today, Ötzi rests at the South Tyrol Museum of Archaeology in Bolzano, Italy, in a custom-built, sub-zero vault designed to mimic the glacial conditions where his remains were found. This permanent state of preservation provides scientists—including those from Eurac Research, headquartered in Bolzano—the opportunity to explore the microscopic world still thriving within the mummy’s desiccated remains. In 2019, scientists from Eurac Research initially described Ötzi’s microbiome in the journal Cell Host & Microbiome and confirmed that it mimicked examples from other early human populations with bacteria rarely found in today’s modern, industrialized societies.

Now, in a new study published in the journal Microbiome, a team of scientists from Eurac Research discovered evidence of cold-adapted yeasts that likely clung to Ötzi during his five-millennia-long dirt nap. The team found traces of these yeasts in skin samples, meltwater in the mummy itself, and in stomach contents. Finding both degraded and modern DNA fragments, the scientists can assume that the yeast have continued to thrive even during the mummy’s current preservation at -6° Celsius. While some of these microbes were likely introduced during Ötzi’s discovery and eventual preservation, the findings also support an ongoing theory that this famous mummy’s remains likely thawed and refroze several times over thousands of years.

“We see continuity here,” Frank Maixner, senior author of the study, said in a press statement. “These yeasts have accompanied Ötzi on his long journey through the millennia.”

To sift through these ancient and modern organisms, the team grew multiple microbe species and produced four viable ones, three of which were capable of using phenol—an ingredient used to rid the mummy of fungal growth—as a food source.

“We want to characterize these yeasts more precisely in terms of their function and systematically investigate their properties,” Mohamed Sarhad, lead author of the study, said in a press statement. “At the same time, we’re considering how they could be put to practical use and would like to experimentally test various potential applications.”

One of those experimental tests? Making a sourdough starter. The idea is that cold-adapted yeast could potentially ferment at room temperature (or even colder). This could save energy since the yeast wouldn’t require additional heating. While the sourdough starter eventually took form, rising as expected in 24 hours, the resulting bread left some room for improvement.

“I’ve never baked bread before—and it showed,” Sarhan said in a press statement. “Bread is currently one of the obvious applications we’re considering; another is beer.”

Cheers to that.