Image taken from the International Space Station of the Atacama Desert and the numerous salt flats in the Andes Mountains along the border of Chile and Bolivia.
Credit: NASA

The Atacama Desert in Chile continues to offer Earth-based clues on searching for astrobiology off-planet.

Recently, a novel type of “biocrust” was discovered in the Atacama Desert, one of the world’s oldest and driest deserts, covering most of its floor. This biocrust is made of prokaryotic cyanobacteria, eukaryotic green algae, fungi, lichens and other microbes.

The harsh conditions under which they thrive in this biocrust – or at least individual strains contained therein – might be suitable candidates for testing their vitality in outer space or under conditions found on Mars.

Credit: Patrick Jung, et al.

A new research paper — “The grit crust: A poly-extremotolerant microbial community from the Atacama Desert as a model for astrobiology” – appears in Frontiers in Astronomy and Space Sciences.

Extra-terrestrial landscapes

According to the research, led by Patrick Jung, a post doctoral researcher at the

University of Kaiserslautern in Germany, the grit crust mediates various bio-weathering activities in its natural habitat.

“These activities prime soil for higher organisms in a way that can be envisioned as a proxy for general processes shaping even extra-terrestrial landscapes,” Jung and colleagues explains. The grit crust as a model for astrobiology “in terms of extra-terrestrial microbial colonization and biotechnological applications that support human colonization of planets.”

Potential fossilization traces of the grit crust depicted by various techniques.
Credit: Patrick Jung, et al.

Jung and associates explain that one of the biggest challenges during human colonization of other planets has been the formation of soil as a weathering product of mainly unweathered rocks found on other planets. “Access to nutrient rich soil would subsequently allow the growth of microorganisms and/or plants in order to support human life,” they suggest.

Wind-blown dust

The atmosphere of the Red Planet is full of dust, with loads that greatly fluctuate with the year’s season. Indeed, that aeolian (wind-blown dust) transport, including microbes, is a likely scenario that could support the microbial colonization of other planets that support human life.

In the Atacama Desert, for example, it has been shown that certain soil-borne microorganisms were transported more than 60 miles (100 kilometers) off the coast towards the hyper-arid core of the Atacama, the researchers point out.

“The ecology of the grit crust, including its extremophile microbial constituents, are unique amongst biocrusts on Earth that can be beneficial for human colonization of other planets or rock bodies such as the Earth’s Moon or Mars,” the research team observes.

Humans on Mars – the reach for the Red Planet.
Credit: Boeing

Consortium of microorganisms

The grit crust’s extremophiles can be used to test their suitability during mass cultivation in photobioreactors (food-, oxygen source for crewed missions), screenings for Chlorophyll F, a photosynthetic pigment which is able to capture light energy in the infrared spectrum.

“For these reasons, the grit crust as a consortium of various microorganisms on a mineral substrate opens up a new opportunity to test hypotheses and ideas in the context of astrobiology that surpasses other biocrusts known on Earth,” Jung and colleagues report.

Currently, the research project “Grit Life” funded by the German Research Foundation, aims to untangle the microbiota of the grit crust based on metabarcoding data applied to a recovery experiment over several years.

To read the full paper – “The grit crust: A poly-extremotolerant microbial community from the Atacama Desert as a model for astrobiology” – go to:

https://www.frontiersin.org/articles/10.3389/fspas.2022.1052278/full

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