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Microscopic Miners: How invisible forces create tropical caves

Featured Image: Scientist Ceth Parker moving through a passageway within an iron formation cave.  Photo courtesy of the University of Akron.

Paper: Enhanced terrestrial Fe(II) mobilization identified through a novel mechanism of microbially driven cave formation in Fe(III)-rich rocks

Authors: Ceth W. Parker, John M. Senko, Augusto S. Auler, Ira D. Sasowsky, Frederik Schulz, Tanja Woyke, Hazel A. Barton

Consider this: microscopic creatures literally moving tons of rock before your very eyes. It seems too fantastical, but maybe not if you’re in the Brazilian tropics. In new work, scientists have detailed these stealthy and microscopic processes, naming a new cave generation pathway called exothenic biospeleogenesis, or “behind-wall life-created” caves.

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Rust to the Rescue?

Featured Image: Shewanella putrefaciens CN-32 (a microbe capable of eating iron) on hematite (a rock containing iron). Image courtesy Environmental Molecular Sciences Laboratory (EMSL). Used with permission.

Paper: Organic matter mineralization in modern and ancient ferruginous sediments

Authors: André Friese, Kohen Bauer, Clemens Glombitza, Luis Ordoñez, Daniel Ariztegui Verena B. Heuer, Aurèle Vuillemin, Cynthia Henny, Sulung Nomosatryo, Rachel Simister Dirk Wagner, Satria Bijaksana, Hendrik Vogel, Martin Melles, James M. Russell, Sean A. Crowe, Jens Kallmeyer

Just as a crow may use a rock to crack a nut, certain microbes can use solid iron to crack open methane.  This consumption limits the amount of methane lost from lakes into the atmosphere, making it a crucial process in mitigating production of greenhouse gasses.  These microbes are abundant in freshwater sediments, and their specialized mechanism for cracking open methane is most likely one of the oldest metabolisms on Earth, providing a modern-day window into the past.

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