Brains
Credit: Eurac Research | Andrea De Giovanni
More than 5,000 years after his death in the Alps, Ötzi the Iceman is still hosting life. Researchers at Eurac Research in Italy have completed the most detailed analysis yet of the microorganisms associated with the world’s most famous glacier mummy, revealing a surprisingly complex ecosystem that includes ancient gut bacteria and cold-loving yeasts that may have accompanied Ötzi since the Copper Age.
The findings, published in the journal Microbiome, provide new insight into both ancient human biology and the unique microbial communities that can survive in extreme cold environments.
Ötzi was discovered in 1991 by hikers high in the Ötztal Alps near the border of Austria and Italy after emerging from glacial ice. Radiocarbon dating later determined that he had died approximately 5,300 years ago, making him one of the best-preserved natural mummies ever found.
To understand the microorganisms associated with the mummy, researchers analyzed ice from Ötzi’s surface, meltwater from inside the body, skin swabs, stomach contents, tissue samples, and even a soil sample collected from the discovery site in 1991. The comprehensive investigation allowed scientists to distinguish between microbes that were present during Ötzi’s lifetime and those that colonized the mummy after death.
Among the most significant discoveries was genetic material from Ötzi’s original gut microbiome. Researchers found bacterial communities that closely resemble those identified in ancient human populations and are rarely seen in people living in modern industrialized societies.
The study also revealed several species of cold-adapted yeasts living within the mummy’s environment. These microorganisms were recovered from skin samples, stomach contents, and meltwater extracted from inside the body.
Genetic analysis showed that the yeasts are related to strains found in some of Earth’s coldest environments, including Antarctica. Scientists believe they originated in the glacier environment and may have remained associated with the mummy for thousands of years. “We see continuity here,” said Frank Maixner, director of the Institute for Mummy Studies at Eurac Research. “These yeasts have accompanied Ötzi on his long journey through the millennia.”
Researchers discovered both heavily degraded ancient DNA and well-preserved modern DNA, suggesting the microorganisms are not simply remnants of the past but may still persist under Ötzi’s current storage conditions. The mummy is preserved at -6°C (21°F) in a high-humidity chamber at the South Tyrol Museum of Archaeology in Bolzano, Italy.
The findings challenge the idea of the mummy as a static archaeological artifact. “Ötzi is not a static relic, but a dynamic biological system,” Maixner said.
One unexpected finding involved conservation treatments used after Ötzi’s discovery. Researchers found that three of the four yeast species possess genes capable of breaking down phenol, a compound previously used to suppress fungal growth on the mummy. Scientists believe the yeasts may have used the chemical as a food source, potentially benefiting from efforts intended to eliminate microorganisms. “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 Sarhan.
Beyond archaeology and conservation, the research may have practical applications. Because the yeasts remain active at extremely low temperatures, scientists are exploring whether they could be used in energy-efficient industrial processes. Early experiments have already produced encouraging results. Sarhan and his team successfully adapted one of the yeasts to create a sourdough starter capable of fermenting dough at low temperatures. “We made some really good dough with it,” Sarhan said.
Researchers are now exploring potential applications in bread making, brewing, and other fermentation industries, where microorganisms that remain active in cold conditions could reduce energy requirements and create new production methods.
It’s remarkable that a 5,000-year-old microbial community could still help shape modern food and industrial processes.
