Salt-Loving Microbe Can Grow Under Mars-Like Conditions: Study | Sci.News

Haloferax volcanii, a model halophilic (salt-loving) archaeon, showed growth during a 160-day experiment simulating Martian subsurface brine, according to a paper published in the journal Applied and Environmental Microbiology. The authors stress the result does not mean life exists on Mars.

“The present-day Martian surface is generally considered inhospitable to life because of low atmospheric pressure, intense surface radiation, global desiccation, and oxidizing chemistry, which has been increasing since the Late Noachian,” said Dr. Adam Robinson from the University of Florida and his colleagues.

“However, shallow Martian subsurface regions where mineralogy has shown groundwater movement may include localized hypersaline environments capable of retaining liquid water and supporting microbial metabolism.”

The study authors focused on Haloferax volcanii, an archaeon known as an extremophile for its ability to tolerate extreme conditions here on Earth.

They kept cultures in a vacuum chamber at 24 millibars, roughly 2% of Earth’s sea-level pressure, filled with carbon dioxide and scrubbed of oxygen. The temperature was held at 21 degrees Celsius (about 70 degrees Fahrenheit).

The microbes sat in extremely salty liquid medium containing either nitrate or perchlorate, both chemicals found on Mars, which the organisms can use in place of oxygen to ‘breathe.’

This pressure could occur inside sealed fluid pockets in salt minerals at depths of about 20 cm (8 inches) below the Martian surface.

“The environment that we’re mimicking in this experiment has not been observed on Mars, but is theorized to exist,” Dr. Robinson noted.

Growth appeared in every low-pressure treatment that contained nitrate or perchlorate, based on increases in optical density, a measure of how cloudy a culture becomes.

The researchers also measured drops in nitrate and perchlorate levels, which did not occur in cell-free controls, suggesting the microbes were metabolizing the chemicals.

Nitrate fell by about 15% to 29% and perchlorate by about 16% to 29% in the Mars-pressure cultures.

Liquid loss stayed below 4% across all treatments over the 160 days. This matters because water normally evaporates rapidly at such low pressures, which has made long-term experiments difficult.

Electron microscope images showed dense biofilm-like structures in the actively growing low-pressure cultures, which were not seen in Earth-pressure controls or in low-pressure cultures that did not grow.

Chemical signatures of carotenoid pigments, which Raman spectroscopy can detect and which have been proposed as possible biosignatures, also remained detectable, though weaker than in oxygen-fed controls.

Growth was significantly lower at 24 millibars than in identical cultures at Earth pressure, according to the team.

The experiment also did not reproduce Mars’s freeze-thaw cycles, radiation, or its full chemistry, and the nutrient-rich growth medium is not representative of the organics thought to be available on Mars.

Cultures were measured only at the start and end of the run, since opening the chamber would have let oxygen in.

“We are adding to the growing body of evidence suggesting that we should consider the possibility of life on Mars today,” Dr. Robinson concluded.

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Adam Robinson et al. Cultivation of halophilic archaea in shallow subsurface Martian conditions has implications for extant life on Mars. Applied and Environmental Microbiology, published online November 5, 2026; doi: 10.1128/aem.01749-26