A team of researchers has successfully baked sourdough bread using yeast recovered from Ötzi the Iceman, the famous mummy preserved in Alpine ice for more than 5,000 years. The experiment was part of a broader study showing that the ancient remains still host a surprisingly active community of microorganisms.
Since his discovery in 1991, Ötzi has offered scientists a rare glimpse into life during the Copper Age. His body, preserved by glacial ice in the Ötztal Alps, has revealed details about ancient diets, health conditions, clothing, tools, and even the events leading to his death.
The latest research turns attention to a less visible aspect of the mummy: its microbiome. Rather than studying microorganisms as mere traces of the past, researchers wanted to know whether some of them could still survive and grow under the cold conditions used to preserve Ötzi today.
A Unique Mix Of Ancient And Modern Microbes
Ötzi died around 5,300 years ago after being struck by an arrow in the back. Hisbody froze in the glacier and remained there until hikers discovered it emerging from melting ice near the border between modern-day Italy and Austria.
Today, the mummy is stored at theSouth Tyrol Museum of Archaeology in Bolzano, Italy. Temperatures are maintained at minus 6 degrees Celsius with extremely high humidity, conditions designed to replicate the environment that preserved him for millennia.
To investigate the microorganisms associated with the mummy, researchers collected swabs from Ötzi’s body, sampled thawed water from inside and around the remains, analyzed museum air, and examined soil from the original discovery site. DNA sequencing revealed two broad groups of microorganisms: those that colonized the body after death in the glacier and those introduced through handling and conservation efforts after the mummy’s discovery.
Mohamed Sarhan, a microbiologist at Eurac Research and lead author of the study, said the microbiome is unusual because it combines organisms from vastly different periods.
“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.”
Cold-Loving Yeasts Take Scientists by Surprise
Among thefindings published in the journal Microbiome,one immediately caught the researchers’ attention. Researchers managed to culture four types of cold-loving yeasts from Ötzi’s skin, stomach contents, and body water: Glaciozyma, Mrakia, Phenoliferia, and Goffeauzyma.
These yeasts are typically associated with some of the coldest environments on Earth, including Antarctica, Arctic ice, and high-altitude regions. Speaking to AFP, Sarhan said the team had not expected to find yeast among the microorganisms recovered from the mummy.
The genetic material of the yeasts showed damage patterns consistent with age, suggesting they may have colonized Ötzi shortly after his death or descended from organisms that did. Researchers also compared samples collected in 2010 and 2019 and found that one genus, Glaciozyma, had become much more abundant over time.
The more recent samples contained DNA that appeared less degraded, a finding the team interpreted as possible evidence of recent or ongoing growth.
From the laboratory to a loaf of sourdough
After successfully growing one of the yeasts, the researchers decided to test its practical potential. The next step was using it to make sourdough bread.
The process proved challenging. Initial attempts failed, and the team spent months refining the culture before achieving a result. Eventually, the yeast performed well enough to produce a successful sourdough. Sarhan told Live Science that the effort paid off:
“It worked,” he said. “As a dough, it was very, very good.”
The study also uncovered findings relevant to Ötzi’s long-term preservation. Researchers identified genes linked to the breakdown of proteins, fats, and collagen, materials that make up human tissues. Some microorganisms also carried genes that could help them degrade phenol, a chemical applied to the mummy after its recovery to suppress fungal growth.
Not all scientists agree on how the findings should be interpreted. Nikolay Oskolkov of the Latvian Institute of Organic Synthesis, who was not involved in the research, stated that samples from only two time points provide limited evidence that the yeasts have been multiplying over thousands of years. In his view, they could represent relatively recent colonists.
