Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


In these microbes, iron works like oxygen


A pair of papers from a UW-Madison geoscience lab shed light on a curious group of bacteria that use iron in much the same way that animals use oxygen: to soak up electrons during biochemical reactions. When organisms -- whether bacteria or animal -- oxidize carbohydrates, electrons must go somewhere.

The studies can shed some light on the perennial question of how life arose, but they also have slightly more practical applications in the search for life in space, says senior author Eric Roden, a professor of geoscience at UW-Madison.

The steamy volcanic vent at Chocolate Pot hot spring in Yellowstone National Park, an iron-rich but relatively cool hot spring where a variety of fascinating microorganisms thrive without oxygen. These microbes respire solid iron much as humans breathe oxygen.

Courtesy of Nathaniel W. Fortney

Animals use oxygen and "reduce" it to produce water, but some bacteria use iron that is deficient in electrons, reducing it to a more electron-rich form of the element. Ironically, electron-rich forms of iron can also supply electrons in the opposite "oxidation" reaction, in which the bacteria literally "eat" the iron to get energy.

Iron is the fourth-most abundant element on the planet, and because free oxygen is scarce underwater and underground, bacteria have "thought up," or evolved, a different solution: moving electrons to iron while metabolizing organic matter.

These bacteria "eat organic matter like we do," says Roden. "We pass electrons from organic matter to oxygen. Some of these bacteria use iron oxide as their electron acceptor. On the flip side, some other microbes receive electrons donated by other iron compounds. In both cases, the electron transfer is essential to their energy cycles."

Whether the reaction is oxidation or reduction, the ability to move an electron is essential for the bacteria to process energy to power its lifestyle.

Roden has spent decades studying iron-metabolizing bacteria. "I focus on the activities and chemical processing of microorganisms in natural systems," he says. "We collect material from the environment, bring it back to the lab, and study the metabolism through a series of geochemical and microbiological measurements."

The current studies focus on bacteria samples from Chocolate Pot hot spring, a relatively cool geothermal spring in Yellowstone National Park that is named for the dark, reddish-brown color of ferric oxide. Related studies deal with a culture obtained from a much less auspicious environment -- a ditch in Germany. Both studies are online, in Applied and Environmental Microbiology and in Geobiology.

During the studies, Roden and doctoral student Nathan Fortney and research scientist Shaomei He explored how the cultured organisms changed the oxidation state -- the number of electrons -- in the iron compounds. They also used an advanced genome-sequencing instrument at the UW-Madison Biotechnology Center to identify strings of DNA in the genomes.

"More than 99 percent of microbial diversity cannot be obtained in pure culture," says He, meaning they cannot be grown as a single strain for analysis. "Instead of going through the long, laborious and often unsuccessful process of isolating strains, we apply genomic tools to understand how the organisms were doing what they were doing in mixed communities."

The researchers found some unknown bacteria capable of iron metabolism, and also got genetic data on a unique capacity that some of them have: the ability to transport electrons in both directions across the cell's outer membrane. "Bacteria have not only evolved a metabolism that opens niches to use iron as an energy," says He, "but these new electron transport mechanisms give them a way to use forms of iron that can't be brought inside the cell."

"These are fundamental studies, but these chemical transformations are at the heart of all kinds of environmental systems, related to soil, sediment, groundwater and waste water," says Roden. "For example, the Department of Energy is interested in finding a way to derive energy from organic matter through the activity of iron-metabolizing bacteria." These bacteria are also critical to the life-giving process of weathering rocks into soil.

Iron-metabolizing bacteria have been known for a century, Roden says, and were actually discovered in Madison-area groundwater. "Geologists saw organisms that formed these unique structures that were visible under the light microscope. They formed stalks or sheaths, and it turned out they were used to move iron."

Roden and He are geobiologists, interested in how microbes affect geology, but the significance of microbes in Earth's evolution is only now being fully appreciated, Roden says. "Eyebrows rose when we contacted the Biotech Center three or four year ago to discuss sequencing: 'Who are these people from geology, and what are they talking about?' But we stuck with it, and it's turned into a pretty cool collaboration that has allowed us to apply their excellent tools that are more typically applied to biomedical and related microbial issues."

Some of the iron-metabolizing bacteria appear quite early on the tree of life, making the studies relevant to discovering the origins of life, but the findings also have implications in the search for life in space, Roden says. "Our support comes from NASA's astrobiology institute at UW-Madison. It's possible that on a rocky planet like Mars, life could rely on iron metabolism instead of oxygen.

"A fundamental approach in astrobiology is to use terrestrial sites as analogs, where we look for insight into the possibilities on other worlds," Roden continues. "Some people believe that use of iron oxide as an electron acceptor could have been the first, or one of the first, forms of respiration on Earth. And there's so much iron around on the rocky planets."



Eric Roden
cell 608-443-9048, office 608-890-0724 

Eric Roden | EurekAlert!

Further reports about: Electrons bacteria iron compounds iron oxide microbes microbial

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Seeking balanced networks: how neurons adjust their proteins during homeostatic scaling.

24.10.2016 | Life Sciences

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

More VideoLinks >>>