New oxygen producing mechanism proposed

March 25, 2010 by Lin Edwards, report

Microscopic image of Methylomirabilis oxyfera under fluorescent light. Image: Max Planck Institute for Marine Microbiology
( -- Photosynthesis is the mechanism by which plants generate oxygen, but new research on a novel type of anaerobic bacteria supports the theory that bacteria produced their own oxygen long before the evolution of photosynthesis.

The research team of Dutch researchers and the University of Queensland's Dr Margaret Butler, working in The Netherlands at the Radboud University in Nijmegen, have found a microbe that makes within itself, which is only the fourth mechanism known by which oxygen is produced on Earth. The others are , which releases oxygen as a waste product, cellular generation of oxygen by bacteria from chlorates and enzymatic conversion of reactive oxygen substances.

The subject of the study, a microbe (provisionally dubbed Methylomirabilis oxyfera) collected from oxygen-starved sediments in drainage ditches and canals in the Netherlands, is one of the so-called NC10 bacteria, first found in the caves under the Nullarbor Plain in Australia. It was thought to be able to convert and nitrite to carbon dioxide, so the researchers carried out experiments that traced labeled nitrogen and oxygen going into and leaving a chamber containing the .

The team found the bacteria could consume methane and were producing oxygen by a previously unknown biochemical process. In the presence of nitrates there was no consumption of methane, but when nitrites were added, the bacteria consumed methane and released nitrogen. The microbiologists proposed the bacteria produce nitrogen and oxygen from two molecules of nitric oxide, which in turn is produced from the nitrites. The oxygen would then be used to burn the methane for energy, with the nitrogen released as a waste product. The enzyme or enzymes used in the process are so far unknown.

The researchers were unable to grow a pure culture of NC10 bacteria (as is often the case for environmental bacteria), so they grew them in a with other microbes, and later reconstructed it from the DNA they extracted from the mixture.

The team sequenced the full genome of the proposed new bacteria and also studied the proteins it was producing. Their analysis of the most highly expressed proteins and the genes sequences led to the suggestion an enzyme was producing the oxygen, although they were not able to identify it. One of the team, Katharina Ettwig, said the cells “make hundreds of unknown proteins, and all of them are candidates.” Some of the genetic sequences suggest the bacteria share metabolic pathways seen in other bacteria, including those consuming methane in oxygen-rich environments.

In the paper published in the journal Nature, Dr Butler said the results tell us that bacteria might have been producing and using oxygen in this novel way when the early Earth’s atmosphere was rich in methane but low in oxygen, and the findings may also be relevant to the study of methane cycles on Earth. The proposed oxygen producing pathway might also allow life to exist in high methane/low (or no) oxygen atmospheres, such as those found on planets and moons in the outer solar system.

Explore further: Methane from microbes: a fuel for the future

More information: Ettwig, K. F. et al. Nature 464, 543-548 (2010).

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5 / 5 (3) Mar 25, 2010
I guess nature still has a few tricks up her sleeve. Who knows what we'll find out next, I can't wait for tomorrow.
5 / 5 (1) Mar 25, 2010
TTTT, bacteria and viruses are absolutely cool creations. They live the longest, are indestructible, and you can do and say anything about them and they won't care and will continue to grow, change and adapt!
5 / 5 (2) Mar 26, 2010
Send some of these guys to Titan, jupiter, saturn, uranus, and neptune....see what happens...
5 / 5 (2) Mar 26, 2010
wish venus had suitable nutrients so we could drop those puppies in and begin terraforming Venus -- It might be a little warm but hey no one lives there and we could strip mine the planet.
3 / 5 (2) Mar 26, 2010
Go ahead and send 'em everywhere! Ultimate grand experiment..
3 / 5 (2) Mar 26, 2010
Go ahead and send 'em everywhere! Ultimate grand experiment..

I am absolutely on board.
1 / 5 (1) Apr 03, 2010
Go ahead and send 'em everywhere! Ultimate grand experiment..

I am absolutely on board.

Same here.

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