Scientists have used yeast from the gut of Ötzi the Iceman to make sourdough bread.
The 5,300-year-old hunter, who was found frozen in the Alps in 1991, has fascinated reseachers for decades.
Now a team has uncovered new insights into the complex microbial ecosystem surrounding Ötzi, revealing that some microorganisms from the glacier where he was found have been associated with him ever since.
Using a range of samples and analytical techniques, scientists were able to separate microorganisms from his lifetime and those that colonised his remains after death, both in the ice and during more than three decades of modern preservation.
Frank Maixner, director of the Institute for Mummy Studies at Eurac Research, said: ‘We see continuity here. These yeasts have accompanied Ötzi on his long journey through the millennia.’
‘According to Dr Maixner, the findings demonstrate that the mummy is ‘not a static relic, but a dynamic biological system’.
In one of the project’s most unusual experiments, scientists reproduced one of the strains of yeast found in Ötzi’s gut. After keeping it alive for three months they were eventually able to produce sourdough bread.
While the process provided a lighter moment in the research, scientists believe the microorganisms may have more significant applications.
Cold-adapted microorganisms could, for example, be used in energy-efficient industrial processes such as low-temperature fermentation.
Their next plan however, is to use the yeast to brew an Ötzi the Iceman beer.
The team identified genetic material from bacteria belonging to Ötzi’s original gut microbiome in samples of internal tissue.
They also made a surprising discovery: cold-adapted yeast species, believed to originate from the glacial itself, still living on the mummy today.
The research involved an extensive investigation of Ötzi and his surroundings.
Scientists analysed ice from the surface of the body and meltwater collected from within the mummy, while also taking numerous swab samples.
They supplemented this with data from previous studies of intestinal tissue and stomach contents.
‘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,’ said microbiologist and lead author Mohamed S. Sarhan.
A soil sample collected from the site where Ötzi was discovered in 1991 and frozen during his recovery was also examined to help trace environmental influences.
Researchers confirmed the presence of genetic material from Ötzi’s original gut microbiome in both the intestinal tract and stomach contents.
First described in a 2019 study conducted with Eurac Research, this ancient microbiome closely resembles the limited number of known gut microbial communities from early human populations.
Such bacteria are rarely found in people living in modern industrialised societies, offering what scientists say is a rare glimpse into humanity’s microbial past.
The newly identified yeasts were isolated from skin samples, meltwater from inside the mummy and stomach-content samples. These highly specialised organisms are adapted to survive in extremely cold conditions.
Genetic analysis showed similarities with strains
found in some of the coldest places on Earth, including Antarctica.
‘The mummy’s conservation conditions are very stable today,” comments Elisabeth Vallazza, director of the South Tyrol Museum of Archaeology, which oversees the mummy’s preservation.
‘Close microbiological monitoring ensures that the mummy suffers no damage. But further research and full conservation efforts are certainly needed to preserve it for many more generations.’
Conservation expert and co-author Marco Samadelli said: ‘The conditions under which glacial mummies are preserved are not yet fully understood. This study expands our knowledge in this area.’
The finding were published in the journal Microbiome.