Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Billions of years ago, microbes were key in developing modern nitrogen cycle

23.02.2009
As the world marks the 200th anniversary of Charles Darwin's birth, there is much focus on evolution in animals and plants. But new research shows that for the countless billions of tiniest creatures – microbes – large-scale evolution was completed 2.5 billion years ago.

"For microbes, it appears that almost all of their major evolution took place before we have any record of them, way back in the dark mists of prehistory," said Roger Buick, a University of Washington paleontologist and astrobiologist.

All living organisms need nitrogen, a basic component of amino acids and proteins. But for atmospheric nitrogen to be usable, it must be "fixed," or converted to a biologically useful form. Some microbes turn atmospheric nitrogen into ammonia, a form in which the nitrogen can be easily absorbed by other organisms.

But the new research shows that about 2.5 billion years ago some microbes evolved that could carry the process a step further, adding oxygen to the ammonia to produce nitrate, which also can be used by organisms. That was the beginning of what today is known as the aerobic nitrogen cycle.

The microbes that accomplished that feat are on the last, or terminal, branches of the bacteria and archaea domains of the so-called tree of life, and they are the only microbes capable of carrying out the step of adding oxygen to ammonia.

The fact that they are on those terminal branches indicates that large-scale evolution of bacteria and archaea was complete about 2.5 billion years ago, Buick said.

"Countless bacteria and archaea species have evolved since then, but the major branches have held," said Buick, a UW professor of Earth and space sciences.

He is the corresponding author of the research, which appears in the Feb. 20 edition of Science. Lead author is Jessica Garvin, a UW Earth and space sciences graduate student. Other authors are Ariel Anbar and Gail Arnold of Arizona State University and Alan Jay Kaufman of the University of Maryland. The work was funded by NASA and the National Science Foundation.

The scientists examined material from a half-mile-deep core drilled in the Pilbara region of northwest Australia. They looked specifically at a section of shale from 300 to 650 feet deep, deposited 2.5 billion years ago, and found telltale isotope signatures created in the process of denitrification, the removal of oxygen from nitrate.

If denitrification was occurring, then nitrification – the addition of oxygen to ammonia to form nitrate – also must have been taking place, Buick said. That makes the find the earliest solid evidence for the beginning of the aerobic nitrogen cycle.

"What this shale deposit has done is record the onset of the modern nitrogen cycle," he said. "This was a life-giving nutrient then and remains so today. That's why you put nitrogen fertilizer on your tomato plants, for example."

The discovery gives clues about when and how the Earth's atmosphere became oxygen rich, Buick believes.

Geochemical examination of stratigraphic samples from the core indicates that atmospheric oxygen rose in a temporary "whiff" about 2.5 billion years ago. The whiff lasted long enough to be recorded in the nitrogen isotope record, then oxygen dropped back to very low levels before the atmosphere became permanently oxygenated about 2.3 billion years ago.

It is unclear why the oxygen level declined following the temporary increase. It could have been that the oxygen was depleted rapidly as it reacted with chemicals and minerals that had not been exposed to oxygen previously, Buick said. Or something could have halted the photosynthesis that produced the oxygen in the first place.

But it seems clear, he said, that the tiniest creatures played a crucial role in completing the nitrogen cycle that life depends on today.

"All microbes are amazing chemists compared to us. We're really very boring, metabolically," Buick said.

"To understand early evolution of life, we have to know how organisms were nourished and how they evolved. This work helps us on both of those counts," he said.

Vince Stricherz | EurekAlert!
Further information:
http://www.washington.edu

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>