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[1] Researchers have discovered that yeast has been thriving in the gut of Oetzi the Iceman, a frozen mummy, for thousands of years. They successfully used this ancient yeast to create a delicious sourdough bread. More than 5,300 years ago, long before the construction of the Egyptian pyramids, Oetzi was traversing the Alps on the border of Austria and Italy when he was fatally struck by an arrow in the back.
[2] He remained frozen in the ice until two German hikers stumbled across his mummified remains in 1991. Since then, his stunningly well-preserved remains have been kept at the same temperature – minus six degrees Celsius – as his icy tomb. This has allowed scientists to carefully study Oetzi, who offers an incredibly rare window into ancient human life.
[3] In the latest research, published in the journal Microbiome, an Italian team found evidence that both ancient and modern microbial life remain active in the frozen body. “What we didn’t expect to find was yeast,” said lead study author Mohamed Sarhan of the Eurac Research institute in the Italian city of Bolzano.
[4] The scientists discovered four different yeasts that can survive sub-zero temperatures in Oetzi’s guts, skin and “brownish” water that melted off his body when he was partially unfrozen. These kinds of yeast only live in very cold conditions, such as Antarctica, and are believed to have entered Oetzi’s body at some point after he died. Genetic analysis revealed “DNA damage levels very comparable to the original microbes” in the Iceman’s guts, suggesting the yeast entered his body soon after death, Sarhan said.
[5] The scientists then reproduced the gut yeast in a fridge. “If you tell anyone you have yeast, they immediately ask: Can we use it for bread?” Sarhan said. So they tried to make a sourdough loaf. “Initially, it didn’t work,” the microbiologist admitted. But after three months of effort, “we had a very, very good sourdough,” Sarhan said.
[6] The study contained more serious possible uses for the yeast. When the mummy was found, it was initially treated as a normal cadaver. A chemical called phenol was used to stop fungus from growing in the body. However, the strange yeast was able to consume the phenol, suggesting that it could help break down the chemical in contaminated environments, the scientists said.
[7] An analysis of Oetzi’s microbiome also revealed a particular kind of gut bacteria that is almost non-existent among modern humans. Though gone from the stomachs of people in the industrialised world, the bacteria have been detected among tribes in Africa and South America.
[8] It has also been found in 3,000-year-old faeces preserved in a salt mine in Hallstatt, Austria, which provides one of the few other available views into the ancient human microbiome. Oetzi and these Bronze Age salt miners ate more fibre and whole grains than modern-day people, Sarhan explained. The study said it “reveals that the Iceman is not a biologically ‘frozen’ time-capsule but rather a complex ecosystem”. It is also too early to say whether the yeast is harming the mummy, Sarhan said, calling for more research.
Source: Agence France-Presse, June 3
