Bacteria That ‘Breathes’ Iron: Microbes That Might Change Our Search For Life In Space

At the Chocolate Pot hot spring in Yellowstone National Park, curious microorganisms are being studied includinfBacteria that utilizes iron the way we use oxygen. These types of previously unknown bacteria respires solid iron the way humans breathe oxygen, and the finding might shed light on how life on earth initially came about. Could it also stir up controversy on where life may exist in other places in the galaxy?

All organisms, even bacteria, soak up electrons during biochemical reactions. We use oxygen to do this, but these interesting microbes found in Yellowstone thrive in the iron-rich hot spring without oxygen, according to a pair of papers from a UW-Madison geoscience lab. This type of bacteria may completely change the way we search for life in space, according to senior author Eric Roden, a professor of geoscience at UW-Madison.

We use oxygen, but some bacteria reportedly can take electron-rich forms of iron and literally eat the iron to get energy that we would get from oxygen. These microbes in the hot spring are said to have evolved in an oxygen-scarce environment to move electrons to iron while metabolizing organic matter.

These bacteria do “eat organic matter like we do,” Roden, who has spent decades researching iron-metabolizing bacteria, says, according to Science Daily. “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.”

The other study of the interesting bacteria comes from a more mundane source: A ditch in Germany. Both studies have been published online in Applied and Environmental Microbiology and in Geobiology.

“More than 99 percent of microbial diversity cannot be obtained in pure culture,” research scientist Shaomei He said. “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.”

Fascinatingly, the researchers say that some unknown bacteria apparently have a unique 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,” He explained, “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,” Roden explained. “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 types are believed to also be imperative to weathering rocks into soil. Iron-metabolizing bacteria was first discovered about a century ago, but Roden and He say that the significance of bacteria in Earth’s evolution is only now being fully understood.

“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,” Roden said.

Roden says we can use the information learned from studying this bacteria to search for life in space, adding that the team’s 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.”

Though people usually believe that finding environments similar to earth’s is needed to find life on other planets, researchers say the possibilities are limitless.

“A fundamental approach in astrobiology is to use terrestrial sites as analogs, where we look for insight into the possibilities on other worlds,” Roden said. “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.”

[Image via Pixabay]