It's cold up here at 2,300 meters, but fortunately the sun is shining. The first snow of this year is already lying on the Corbassière glacier in mid-November. While the team is setting up at the stream just below the glacier snout, unpacking the experiment kit they have brought with them from their cases, Tom Battin and Hannes Peter are beside themselves with excitement; they take stones from the stream and pass them around. What can there possibly be to see at these inhospitable, very wintry altitudes? A great dea las it happens, and you don't have to be an expert to soon realise that. Some of the stones are covered with a greenish coating of slime, and in some places in the stream it grows like Gandalf's beard. And what is the temperature of the water? 0.01 degrees. Is there any other life around? There's not much to see: a few lichens on the stones, a few hardy plants in sheltered spots on the slopes. The stream may hardlyflush many nutrients out of the glacier bed, but it's enough for these microorganisms. Hannes Peter specialises in river ecosystems, and he knows that this is the best time for biofilms. Not too much current, but there is plenty of light. The conditions couldn't be any better.

What are biofilms? This has nothing to do with wildlife documentaries, they are communities of micro-organisms. Most people are aware of them from medicine, where biofilms are often problematic because they prove to be very resistant. It is estimated that some 80 percent of chronic infections are caused by biofilms. They are also resistant up here, on the glacier, where they have found a perfect niche. “Biofilms have been around for three and a half billion years and are a very original and successful form of life on Earth,” explains Tom Battin, professor at EPFL and head of the Stream Biofilm and Ecosystem Research Laboratory.

“This research is of global importance and fits in perfectly with the new Centre for Alpine and Polar Environmental Change at EPFL Valais.” Martin Vetterli, President of EPFL

Perhaps they were the beginning of life as we know it: more complex life forms with organs that share tasks. Microorganisms became “sedentary” at some point. They began to form a slimy substrate, into which other species subsequently also settled. Higher life must have started as a microbial commune. The communities soon became megacities, with thousands of taxa, which survived, for example, in metabolic processes and in defence against enemies. Battin calls it “sociomicrobiology”.

The biofilms up here are the basis of stream ecosystems and, to a certain extent, the start of the food chain. “The microorganisms orchestrate essential biochemical processes in streams and rivers, and they are the least researched.” Especially up here where the water emerges. “We know more nowadays about microbial life in the depths of the ocean than we do about the water in the streams that drain the roof of our planet,” says Battin.

He wants to change that. This is why he has recruited Michael Styllas, who normally leads expeditions into the high mountains and who is now using a shovel to fetch sediment from the stream. In the next few years, a team led by Styllas will travel the globe, investigating around 200 glacial streams in various geographical environments.

Battin believes that there are remains of ancient ecosystems up here in the snow and ice. It is possible that they have hardly changed. Battin and Peter are hoping to find a core microbiome, the lowest common denominator of biofilm life. “We want to know what genetic repertoire these communities need. That way, we can understand how they manage to survive under these conditions.” And that is all the more important as these conditions are changing rapidly at the moment. How are stable communities formed in an environment that is extremely unstable, especially now? To understand this, we need to take a look into the past, and at the same time, one into the future. How are these biofilms adapting to climate change?

On the Corbassière glacier, it’s a matter of learning what to do and testing the materials. Who to position where along the stream and how to coordinate the experiments? Everything runs according to a precise plan and has to function reliably, whether the sun is shining, or whether it is cloudy and windy. Some experiments are carried out in situ at the stream, while more complex analyses follow later in the laboratory. The precise sequencing takes place there, because the researchers are particularly interested in the metagenomics and metatranscriptomics of the microbes in the biofilms.