Organic Soil Solids May Aid Bacteria

MADISON, Wis., May 26 (UPI) — U.S. and German scientists say they’ve determined “mineral-breathing” bacteria found in many oxygen-free environments might be “carbon-breathing” as well.

The researchers, led by University of Wisconsin-Madison Professor Eric Roden, said oxygen-free, or anaerobic, environments contain microbes sometimes described as “mineral-breathing” because they use iron oxides and other minerals in the same way we use oxygen. The new study suggests bacterial respiration might also be accelerated by solid organic soil compounds.

The scientists said they found iron oxide-breathing bacteria can do the same with insoluble organic substances, formed when plants and other organic materials biodegrade in soils and sediments.

“The reason this is so important is that when the humic substances are reduced — that is, when they go from having less electrons to having more electrons — they are very reactive with other things, in particular iron oxides,” Roden said. “All kinds of things follow iron oxides — organic contaminants, inorganic contaminants, energy flow, mineral transformations on Earth, speculation about possible iron-based microbial life on other worlds,” Roden said, adding insoluble organic compounds in the soil are a “player in that whole picture that no one had recognized before.”

The research is reported in the early online edition of the journal Nature Geoscience.

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