Life on Mars has yet to be discovered, but it’s interesting to explore the conditions under which this is possible. A team led by the Technical University of Berlin (TU Berlin) and the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) studied the cellular processes that regulate the adaptation of microorganisms to perchlorate. If microorganisms could genetically adapt their stress response to this salt found in some deserts and on Mars, they might survive on the Red Planet.

Life as we know it requires the presence of energy and CHNOPS. This abbreviation stands for carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Micronutrients and liquid water are also indispensable. Much of this is available on Mars: energy can be provided by sunlight or chemical processes, carbon can be obtained through a thin but carbon dioxide-rich atmosphere, and other essential elements are abundant in what is called regolith on the planet’s surface.

However, liquid water is a problem due to the low atmospheric pressure of about 6 millibars (for comparison, the average air pressure on Earth is about 1 bar) and the average temperature is below zero. One of the few ways to get water near the Martian surface is by melting it to form temporarily stable salt solutions.

In this process, salt absorbs water from the atmosphere and dissolves in it. There are many hygroscopic salts on Mars, including perchlorates (ClO). ₄^–), easily absorbs water from the atmosphere and lowers the freezing point of water. They are also sometimes found in very dry deserts on Earth. This water is theoretically sufficient to support the metabolism of certain groups of microorganisms. However, until now, little was known about how perchlorates cause stress in the cell and in what form.

“To understand potential microbial life on Mars, it is important to find out how microorganisms cope with such stressors, because microbes will only be able to cope with high salt concentrations and actually use salts such as melting and lowering the freezing point if they develop a good stress response,” said TU Berlin. First author from Jacob Heinz.

The research team used a proteomics protocol developed by the Robert Koch Institute (RKI) to analyze the perchlorate-specific stress response of the yeast Debaryomyces hansenii and compare it with commonly known salt stress adaptations. The researchers found that stress responses to sodium chloride and sodium perchlorate share many common metabolic features; for example, the same signaling pathways, increased energy metabolism or osmolyte formation.

“However, we have also identified several new stress responses specific to perchlorate. For example, protein glycosylation and cell wall remodeling are likely to stabilize protein structures and cell membranes. Co-author Hans-Peter Grossart of the IGB said, “These stress responses occur on Mars. It will also be of great importance for the predicted life.”

“If we’re looking for life on Mars, we have to keep an open mind because local Martian microbes – if they exist – have certainly adapted to the Martian environment through different biochemical processes that might not have occurred on Earth,” Dirk said. Schulze-Makuh is a co-author of the study and a researcher at IGB and TU Berlin. But if we examine how organisms on Earth cope with stressors such as perchlorates on Mars, we will have the first clues as to how life on Mars can cope with the harsh environmental conditions.”