In the intestines of a frozen mummy named Ötzi, discovered in the Alps in 1991scientists found that yeast had developed… with which they made bread.
This man from the Bronze Age, known as «the snowman» and who died from an arrow in the back 5,300 years agohad a very unusual natural mummification process: its cells, literally frozen, retained their moisture.
The body, discovered by hikers on September 19, 1991 in a glacier on the border between Italy and Austria, is so well preserved that since then it has been a mine of information for researchers.
His remains, preserved in the museum of Bolzano (Italy), are kept at the same temperature (-6 °C) than where they were found.
These conditions did not prevent microorganisms (both ancient and recent) from remaining active in the frozen body, according to a study published in the journal Microbiome.
«What we didn’t expect was to find yeast,» says Mohamed Sarhan, lead author of the study and researcher at the Eurac Research institute in Bolzano.
A «very good» sourdough
Scientists discovered four different types of yeast capable of surviving sub-zero temperatures in Ötzi’s intestines, on his skin and in «brownish» water from the mummy’s partial thawing.
These microscopic fungi only live in very cold environments, such as Antarctica or the Alps.
Genetic analysis revealed «levels of DNA damage very comparable to those of the original microbes» present in the Iceman’s intestines, suggesting that the yeast entered there shortly after his death, explains Mr Sarhan.
«These yeasts accompanied Ötzi on his long journey through the millennia,» says Frank Maixner, co-author of the study, in a statement.
The scientists then reproduced these mushrooms in a refrigerator.
«When you say you have yeast, they immediately ask you: can it be used to make bread?» says Sarhan.
And that was precisely what the team did.
«At first, it didn’t work,» says the microbiologist. But after three months of trying, «we got a really, really good sourdough»he says, adding that the team is now considering brewing beer.
The study also mentions other more serious purposes for these microorganisms.
When the mummy was discovered, it was initially treated as a normal corpse, with a chemical, phenol, used to prevent fungal growth.
But the yeast was able to degrade the phenol. That is why scientists believe that, in the future, it could be used to decompose this chemical in contaminated environments.
Fibers and whole grains
This fungus was not the only surprising discovery on Ötzi’s body.
An analysis of its microbiota revealed the presence of an intestinal bacteria almost non-existent in modern humans. Although it disappeared from the stomachs of the populations of industrialized countries, it has been detected in some tribes in Africa and South America.
It was also found in 3,000-year-old excrement preserved in a salt mine in Hallstatt, Austria, one of the few other sources that allows us to observe ancient human microbiota.
Ötzi and these Bronze Age salt miners They consumed more fiber and whole grains than modern humansSarhan points out.
The study concludes that «Iceman is not a biologically ‘frozen’ time capsule, but rather a complex ecosystem.»
Nikolay Oskolkov, a researcher at the Latvian Institute of Organic Synthesis who was not involved in the study, explains that it is interesting to note that «the microbiota of the ‘iceman’ is not ‘frozen’.»
But the researcher, who had previously discovered fungi in the mummy’s intestines, points out that the yeast samples were only taken in 2010 and 2019.
This represents «very little evidence that yeasts have multiplied over the millennia,» he considers, estimating that they are «relatively recent elements of the mummy’s body.»
AFP Agency.
GML
