Microbes in The Ocean Depths Can Make Oxygen Without Sun. This Discovery Could Be Huge

For most of life on Earth, oxygen is essential, and it usually requires sunlight to produce that oxygen. But in an exciting twist, researchers have caught an ordinary microbe living in the ocean breaking all the rules.

Scientists have discovered that there is a microbe called Nitrosopumilus maritimus and many of its cousins, known as ammonia oxidizing archaea (AOA), can survive in dark environments that deplete oxygen by producing oxygen on their own. They do so using an unprecedented biological process.

Although it has previously been established that these microbes can live in oxygen-deficient environments, what has not been clear is what they do there – and how they stay alive for as long as they them. That was the inspiration behind this new research.

“These men are very abundant in the oceans, where they play an important role in the nitrogen cycle,” said microbiologist Beate Kraft, from the University of Southern Denmark.

“For this they need oxygen, so it’s been a long-standing puzzle why they’re also very abundant in non-oxygenated waters. We thought, do they hang out there with no function? Do they our kind of ghost cells.? “

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

The team wanted to take a closer look at what would happen when all available oxygen disappeared, and no sunlight to produce new oxygen. The same scenario occurs when N. maritimus moving from oxygen-rich to oxygen-depleted waters.

What they found was surprising: the microorganisms produced their own oxygen to create nitrite, with nitrogen gas (dinitrogen) as a by-product.

“We found out how they used up all the oxygen in the water, and then to our surprise, within minutes, oxygen levels started to rise again,” said geobiologist Don Canfield, from the University of Southern Denmark. “That was really exciting.”

At present, the researchers are not sure how the microbes pull off this trick, and the amount of oxygen produced seems relatively small (just enough for their own survival) – but it looks different from the oxygen bit. -the sunlight processes we already know.

What the new path shows is that oxygen production is coming from it N. maritimus is linked to its production of gaseous nitrogen. The microbes somehow convert ammonia (NH3) in nitrite (NO2) – a process they use to metabolize energy – in an oxygen depleting environment.

This, in turn, requires them to make their own oxygen, of which the team has found traces, together with a by-product of nitrogen gas (N2).

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

“If this way of life is prevalent in the oceans, it certainly forces us to rethink our current understanding of the marine nitrogen cycle,” Kraft said.

“My next step is to investigate the phenomenon we observed in our laboratory cultures in oxygen depleted waters in various oceanic locations around the world.”

The research has been published in Science.


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