As we speak, the glaciers in the mountains worldwide are shrinking owing to climate change,
and this at unprecedented pace, and what we ask is what is the microdiversity that we may be losing
as the glaciers shrink and as the streams that they feed are changing, and ultimately disappear.
To address this question, we conduct expeditions all around the world,
and we bring back home samples of the sediments,
but also of the water from these glacier fed streams that we then analyze in our lab.
Today, we understand the microbial life and the associated biogeochemistry in the deepest and most
remote ocean worldwide better than in the stream that literally drained the roof of our planet,
and these are the glacier fed streams. We also understand that it's the microbes that orchestrate
the global biogeochemical cycles, and that's why we thought, let's do it now before it is too late.
In the team of four, we go sample all these streams in many locations across the globe.
So we do basically mountaineering to get to the sampling points
where we do the whole sampling procedure, plus the field experiments.
The idea is to study the whole ecology of this strange environment.
We perform really different analysis, from the minerals of the bedrock, to the bacteria,
to the nutrients that are in the water.
We collect the sediments in the stream, we sieve it, to have a certain range of sediment,
and then we fill vials that will be used to make analysis.
As the samples arrive in our laboratory at EPFL, we do various analysis that at the end of the day
will tell us what are the microorganisms that do well in these extreme ecosystems,
and what are the ecological strategies that they have evolved
over geological time scales so that they can live up there.
We measure a number of parameters that relate to the biomass of the biofilms
that we sample from these glacier streams.
Among these is for instance the amount of chlorophyll A, which is a proxy for the algal biomass,
but we also count the number of bacterial cells.
We measure for instance the biomass production by leucine incorporation, or we measure the activity of extracellular enzymes.
All samples that come in are used to extract DNA.
This DNA is subsequently used in two different metagenomic analysis.
In the first analysis, we amplify two specific genes;
the 16S rDNA and the 18S rDNA, which we will then sequence.
In the second analysis, we aim to reveal the genomes of certain microorganisms out of our community,
and for this we use shotgun metagenomic analysis.
The diversity of the microbes that you encounter in these streams is way higher than expected,
and whether you go to the Swiss alps or to Ecuador for instance, you find more or less always the same
microbial groups or species in there. That's a strong indication actually
that these communities are well adapted to the extreme environment that they encounter in these ecosystems.
So what we also try to do is exploring new avenues to kind of connect the biogeochemistry
in these streams to the structure and the function of the microbiome in there,
and this is very important if we want to make predictions into the future
of how these streams and their microbiome is changing owing to the climate change,
and to the fact that the glaciers that they are still feeding today are disappearing tomorrow.