Eduard Egarter-Vigl (left) and Albert Zink (right) take a sample from the Iceman in November 2010.
For now, researchers are primarily celebrating a unique snapshot of the microbial life inside one famous - and somewhat unfortunate - mummy from ancient Europe.
He has died 5,300 years earlier after getting struck by an arrow.
Its contents could help re-write human prehistory.
A detailed genetic analysis of the stomach led to the discovery of H. pylori DNA. H. pylori is now the oldest microbe to be genetically mapped.
And because bacteria DNA mutates faster than human DNA, studying H. pylori as a marker can give researchers a higher-resolution look at how human populations have moved and mingled over the millennia.
Ötzi the Iceman had a stomach bug.
Modern strains of the bacteria are categorized according to geographic location, and can be traced back to different ancestral sources. But as Ötzi still carried the original Asian strain, this may not have been the case.
That suggests the north Indian strain once belonged to most prehistoric Europeans, prior to an influx of farmers from the Middle East into the continent more than 4,000 years ago.
Because Iceman's strain is more closely related to Asian than various Asian-African hybrids that exist today, this finding also suggests that Asian and African strains had not yet mixed at the time that the Iceman lived. The Iceman seems to have been infected with a virulent strain.
The Iceman was discovered in 1991 by a German couple vacationing in the Italian Alps. In fact, for several years H. pylori analysis could paint a much better picture of human migration than genetic analysis could.
The Iceman's H. pylori did carry a tiny amount of northeast African DNA: about 6.5 percent. Only three such strains have ever been detected in modern Europeans. The researchers add to the growing evidence that Europe has witnessed many migrations.
"The wave of migration that brought the African Helicobacter pylori into Europe had not occurred, or had not occurred in earnest, by the time the Iceman was alive", Moodley concluded.
The bacterial infection can cause stomach ulcers and gastritis.
"So we thought it was extremely unlikely that we would find anything because Ötzi's stomach mucosa is no longer there", he said.
With or without ulcers, Ötzi's life was far from comfortable.
As for Oetzi's health, the stomach bug was probably the lesser of his worries, as it had already been determined he had arthritis, heel fractures and possibly Lyme disease.
"In the end it was, for sure, a tough life in this time period, but with regard to his life circumstances I think he was still in a quite good shape", Zink says.
"We were able to solve the problem once we hit upon the idea of extracting the entire DNA of the stomach contents", said Frank Maixner from EURAC.
By examining the DNA, scientists were able show through the type of DNA sequence present and the degradation of the DNA that the bacteria was from the Iceman and not some other form of contaminant. "The attractive thing is the paper sheds light on one hypothesis about ancient human migration, which is wonderful".
