Microbes deep in the ocean can make oxygen without a sun. This discovery could be huge

For most life on Earth, oxygen is essential, and sunlight is usually required to produce this oxygen. But in an exciting twist, researchers have discovered a common ocean-dwelling microbe that breaks all the rules.

Scientists have found that a microbe called Nitrosopomylus Maritimos And many of its cousins, called oxidizing ammonia archaea (AOA), are able to survive in dark, oxygen-depleted environments by producing oxygen on their own. They do this using a biological process that has never been seen before.

Although it has been shown that these microbes can survive in environments where oxygen is scarce, what has not been clear is what they get there and how they survive throughout their existence. This was the inspiration behind this new research.

“These guys are abundant in the oceans, where they play an important role in the nitrogen cycle,” says microbiologist Pete Kraft, from the University of Southern Denmark.

“That’s why they need oxygen, so it has been a longstanding mystery why they are also so abundant in waters where there is no oxygen. We thought, do they spend time there without a job? Are they some kind of ghost cell?”

Collect a bucket of seawater from the ocean, and every fifth cell will be one of these creatures – that’s how common they are. Here the researchers removed the microbes from their natural habitat and transported them to the lab.

The team wanted to get a closer look at what would happen when all available oxygen was gone, and there was no sunlight to produce new oxygen. The same scenario happens when n. Maritimos It moves from oxygen-rich water to oxygen-depleted water.

What they found was something unexpected: The microorganisms produced their own oxygen to form nitrite, with nitrogen gas (dinitrogen) as a byproduct.

“We saw how they used up all the oxygen in the water, and then to our surprise, within minutes, the oxygen levels started to rise again,” says geologist Don Canfield, from the University of Southern Denmark. “That was very exciting.”

Currently, the researchers aren’t sure how the microbes can do this trick, and the amount of oxygen produced appears to be relatively small (just enough for them to survive) — but it looks different than a little oxygen. – Without the sunshine processes we already know.

What the new pathway shows is that oxygen production from it n. Maritimos It is related to its production of gaseous nitrogen. Microbes somehow convert ammonia (NH .).3) to nitrite (NO2) – a process they use to metabolize energy – in an oxygen-depleted environment.

This in turn requires them to produce their own oxygen, traces of which the team detected, along with the byproduct of nitrogen gas (N2).

This process removes bioavailable nitrogen from the environment – this is a new wrinkle in the nitrogen cycle, which supports all ecosystems. This finding could have “far-reaching” consequences, and this needs further investigation.

“If this lifestyle is so pervasive in the oceans, it certainly forces us to rethink our current understanding of the marine nitrogen cycle,” Kraft says.

“My next step is to investigate the phenomenon we’ve seen in lab cultures in oxygen-depleted waters in different ocean regions around the world.”

The search was published in Science.


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