A species of archaea called Metallosphaera sedula is capable of growth on stony meteorites, utilizing metals trapped within these extraterrestrial objects as the sole energy source, according to new research led by University of Vienna astrobiologists.
SEM image showing Metallosphaera sedula cells colonizing the surface of the NWA 1172 particles. Image credit: Milojevic et al, doi: 10.1038/s41598-019-54482-7.
Metallosphaera sedula is a metallophilic archaeon that lives in hot acidic conditions (73 degrees Celsius and pH 2) and colonizes various metal-containing ores.
Previous studies showed that this microorganism can grow on Martian soil simulants, actively colonizing artificial extraterrestrial materials.
In the new work, University of Vienna astrobiologist Tetyana Milojevic and her colleagues explored the physiology and metal-microbial interface of Metallosphaera sedula, living on and interacting with a real extraterrestrial material — the chondrite meteorite Northwest Africa 1172 (NWA 1172).
“Cells of Metallosphaera sedula rapidly colonize the meteoritic material, much faster than the minerals of terrestrial origin,” the researchers said.
“Meteorite-fitness seems to be more beneficial for this ancient microorganism than a diet on terrestrial mineral sources.”
The study authors traced the trafficking of meteorite inorganic constituents into a microbial cell and investigated iron redox behavior.
Combining several analytical spectroscopy techniques with transmission electron microscopy, they revealed a set of biogeochemical fingerprints left upon Metallosphaera sedula growth on NWA 1172.
“Our investigations validate the ability of Metallosphaera sedula to perform the biotransformation of meteorite minerals, unravel microbial fingerprints left on meteorite material, and provide the next step towards an understanding of meteorite biogeochemistry,” Dr. Milojevic said.
The results were published in the journal Scientific Reports.
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T. Milojevic et al. 2019. Exploring the microbial biotransformation of extraterrestrial material on nanometer scale. Sci Rep 9, 18028; doi: 10.1038/s41598-019-54482-7
