A creature that feeds on hydrogen in the dark

In some dark ecosystems, the lack of light makes photosynthesis impossible.

In that environment, life is maintained by chemical energy.

The role of chemical synthesis is very similar to that of photosynthesis, except that the process of chemical synthesis does not require the participation of light.

Scientists have always hoped to better understand how chemical nutrients from the earth provide fuel for the chemically synthesized biosphere.

Recently, a team of scientists has gained new insights into the survival of microorganisms under ice caps and glaciers through data collected from habitats covered by ice and snow around the world.

They also recognized the role these creatures played in the continuation of life in the ice age, and even in those desolate environments on other planets.

Their research results have been published in the recent Proceedings of the National Academy of Sciences (PNAS).

The researchers analyzed sediment samples collected from two locations, one from Robertson Glacier in Alberta, Canada, and the other from Kotlujokull Glacier in Iceland, and studied how water and microorganisms interact with the bedrock under the glacier of.

When talking about the source of inspiration for this research, the author of the paper, Eric Boyd, said that they have always discovered the existence of organisms supported by hydrogen in such an environment under ice.

At first they couldn't understand, because they couldn't imagine where the hydrogen under the glacier came from.

Later, they discovered that through a series of physical and chemical processes, the silicon-rich bedrock under the glacier would be ground into tiny mineral particles by the heavy ice above.
When these mineral particles were combined with the glacier meltwater, hydrogen gas was released.
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What is even more exciting for researchers is that the microbial communities under the glacier can combine hydrogen and carbon dioxide to produce more organic matter (ie biomass) through a chemical synthesis process.

In order to better understand what these chemically synthesized microorganisms did, the researchers brought sediment samples from Canada and Iceland back to the laboratory and cultivated living biological samples found in the sediments.

They want to see if these organisms can continue to grow in a laboratory environment.

However, in the process of experimental operation, the researchers faced a more difficult difficulty: the microorganisms they were interested in depend on hydrogen to grow, and most of these organisms are some anaerobic bacteria, which means that when they are in contact with oxygen, It is very likely to die.

Therefore, in the process of preparing the experiment, putting the sample in the bottle has become the most critical and difficult step in the experiment process.

This process needs to remove all oxygen as quickly as possible, so as to ensure that the target creature will not be killed.

 Kotlujokull is the fourth largest glacier in Iceland.
There are a large number of microorganisms here.
Their lives are maintained by the hydrogen produced by weathering the basalt bedrock.

| Image source: Eric S.
Boyd Through several months of observation, researchers have not only discovered the growth of these biological communities in the laboratory environment, but also observed the impact of the type of bedrock under the glacier on hydrogen production, and the effect of hydrogen Production in turn affects the existence of microbial communities that can better adapt to hydrogen metabolism.

The Kotlujokull Glacier is located on top of the basalt bedrock, while below the Robertson Glacier is the carbonate bedrock.

The results showed that samples collected from Kotlujokull Glacier produced much more hydrogen than samples collected from Roberson Glacier.

The researchers also discovered that when microorganisms use hydrogen to produce energy, they also absorb carbon dioxide from the air to multiply and grow.

This ability to "fix" carbon is a key step in the climate regulation process, and it is another similarity between this chemical synthesis and plant photosynthesis.

Nowadays, glaciers and ice sheets cover about 10% of the world's land, and this number is smaller than that of the Earth in the past.

Researchers believe that the activities of microorganisms may have had a major impact on the Earth’s climate, both in the past and in the present.

According to researchers, scientists have long known that microorganisms living under ice sheets or under glaciers have the ability to fix carbon, but they have never really understood how they do this.

The new research work shows that these organisms can not only produce their own "fixed" carbon and achieve complete self-sufficiency, but they also do not need the help of sunlight like most other organisms.

What can we learn from this? Astrobiologists have been looking for life that may exist on the solar system or other planets outside the solar system.
A key parameter for assessing the habitability of a planet is water and energy.

The new findings indicate that self-sustaining microbial communities can thrive in icy environments by producing hydrogen, which is a key piece of information for identifying whether other planets have potentially habitable environments.

We have already found evidence of glaciers on many other planets, but we don’t know if there is life there.

Now, scientists may be able to think about whether there are microbes living under glaciers on planets that have bedrock similar to the bedrock involved in this study.
The authors of the new study believe that the answer should be yes.

Reference source: https://phys.
org/news/2020-12-hydrogen-supported-life-beneath-glaciers.
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