For more than 5,000 years, Ötzi the Iceman has carried an invisible community of microbes through ice, time, and modern museum preservation. Now, scientists have taken the most detailed look yet at this microbial ecosystem, separating the microorganisms that accompanied Ötzi in life from those that arrived after his death and during decades of conservation.

By analyzing a wide range of samples with multiple genetic and microbiological techniques, the researchers identified traces of bacteria from Ötzi’s original gut microbiome in internal tissues. They also uncovered an unexpected group of cold-adapted yeasts that likely originated in the glacier environment and have remained associated with the mummy to this day.

The findings, published in the journal Microbiome, offer new insights into the long-term preservation of ancient remains and the remarkable survival strategies of microorganisms in extreme cold.

The investigation was extensive. Researchers analyzed surface ice, meltwater collected from inside the mummy, and numerous swab samples. They also incorporated data from earlier studies of intestinal tissue and stomach contents. To better understand environmental influences, the team examined a soil sample from the discovery site that had been collected and frozen during Ötzi’s recovery in 1991.