Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Iron: A biological element?

26.06.2015

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

That's the upshot of a study published this week in the Proceedings of the National Academy of Sciences (PNAS). The findings have meaning for fields as diverse as mining and the search for life in space.


By studying iron extracted from cores drilled in rocks similar to these in Karijini National Park, Western Australia, UW-Madison researchers determined that half of the iron atoms had originated in shallow oceans after being processed by microbes 2.5 billion years ago.

Courtesy of Clark Johnson

Clark Johnson, a professor of geoscience at the University of Wisconsin-Madison, and former postdoctoral researcher Weiqiang Li examined samples from the banded iron formation in Western Australia. Banded iron is the iron-rich rock found in ore deposits worldwide, from the proposed iron mine in Northern Wisconsin to the enormous mines of Western Australia.

These ancient deposits, up to 150 meters deep, were begging for explanation, says Johnson.

Scientists thought the iron had entered the ocean from hot, mineral-rich water released at mid-ocean vents that then precipitated to the ocean floor. Now Johnson and Li, who is currently at Nanjing University in China, show that half of the iron in banded iron was metabolized by ancient bacteria living along the continental shelves.

The banding was thought to represent some sort of seasonal changes. The UW-Madison researchers found long-term swings in the composition, but not variations on shorter periods like decades or centuries.

The study began with precise measurements of isotopes of iron and neodymium using one of the world's fastest lasers, housed in the UW-Madison geoscience department. (Isotopes, forms of an atom that differ only by weight, are often used to "fingerprint" the source of various samples.)

Bursts of light less than one-trillionth of a second long vaporized thin sections of the sample without heating the sample itself. "It's like taking an ice cream scoop and quickly pulling out material before it gets heated," Johnson explains.

"Heating with traditional lasers gave spurious results."

It took three years to perfect the working of the laser and associated mass spectrometry instruments, Li says.

Previous probes of the source of banded iron had focused on iron isotopes. "There has been debate about what the iron isotopes were telling us about the source," Li says. "Adding neodymium changed that picture and gave us an independent measure of the amount coming from shallow continental waters that carried an isotopic signature of life."

The idea that an organism could metabolize iron may seem strange today, but Earth was very different 2.5 billion years ago. With little oxygen in the atmosphere, many organisms derived energy by metabolizing iron instead of oxygen.

Biologists say this process "is really deep in the tree of life, but we've had little evidence from the rock record until now," Johnson says. "These ancient microbes were respiring iron just like we respire oxygen. It's a hard thing to wrap your head around, I admit."

The current study is important in several ways, Johnson says. "If you are an exploration geologist, you want to know the source of the minerals so you know where to explore."

The research also clarifies the evolution of our planet -- and of life itself -- during the "iron-rich" era 2.5 billion years ago. "What vestiges of the iron-rich world remain in our metabolism?" Johnson asks. "It's no accident that iron is an important part of life, that early biological molecules may have been iron-based."

NASA has made the search for life in space a major focus and sponsors the UW-Madison Astrobiology Institute, which Johnson directs. Recognizing unfamiliar forms of life is a priority for the space agency.

The study reinforces the importance of microbes in geology. "This represents a huge change," Johnson says. "In my introductory geochemistry textbook from 1980, there is no mention of biology, and so every diagram showing what minerals are stable at what conditions on the surface of the Earth is absolutely wrong."

Research results like these affect how classes are taught, Johnson says. "If I only taught the same thing, I would be teaching things that are absolutely wrong. If you ever wonder why we combine teaching and research at this university, geomicrobiology gives you the answer. It has completely turned geoscience on its ear."

Contact:

David Tenenbaum
djtenenb@wisc.edu
608-265-8549

Clark Johnson
clarkj@geology.wisc.edu (preference)
608-262-1710

http://www.wisc.edu 

Clark Johnson | EurekAlert!

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>