There is no longer any radioactive waste in the tunnels.

The site has instead become a research site where researchers investigate how viruses and bacteria behave in extreme environments.

Now completely new viruses and a living bacterial and viral community have been discovered.

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An ecosystem of bacteria and fungi lives in the cracks in the rock.

Photo: Olof Peterson / SVT

- Through large-scale sequencing, we have found completely new viruses that infect many different types of bacteria.

It was particularly interesting to discover viruses that infect bacteria of the newly discovered group of Patesci bacteria, something no one has done before.

And the viruses and bacteria are active.

Because the virus kills its host bacteria, they release carbon and nutrients, which means that other bacteria can grow, says Karin Holmfeldt, associate professor of ecology, in a press release.

Understand the origin of life

The work down in the deep tunnels gives researchers an opportunity to compare structures from bacteria that are alive now, and fossils that can be hundreds of millions of years old.

It can be used to understand the history of life on earth and when looking for life on other planets, such as Mars.