It certainly does not seem inconceivable, researchers have to conclude after research in the Martian Atacama desert.

Chile’s Atacama Desert is one of the driest places on Earth. On average, only 0.5 millimeters of precipitation falls on an annual basis. Partly due to the virtually lack of a cloud cover, the Atacama is perfect for observing the universe and that is why we here include the Very Large Telescope from ESO. But the presence of that telescope isn’t the only reason astronomers like to travel to the desert; Due to the exceptionally arid nature of the Atacama Desert, the area is also seen as a good analogy for Mars. That is why – in an attempt to get a better grip on the habitability of Mars – research is also regularly conducted in the Atacama Desert into what lives there. And those studies have shown that even in this inhospitable and bone-dry desert, a wide range of bacteria can survive. And that cautiously suggests that Mars may also be (or have been) a home for bacteria.

viruses

But it may not stop with bacteria, suggests a new study published in the journal mSystems. Because researchers have now also discovered viruses in the Atacama Desert. And again, if they manage to hold their own there, they might also be able to do so on the also bone-dry Mars.

Very diverse and plentiful

On the one hand, it is not very surprising that the Atacama Desert harbors viruses, researcher Yunha Hwang says in conversation with Scientias.nl. “Where there are bacteria, there are often viruses.” And so bacteria have already been identified in the Atacama Desert. And yet the results of their study somewhat surprised the scientists. “What has surprised us is the enormous diversity and abundance of viruses in the Atacama Desert, because the diversity and abundance of bacteria in that same desert is quite limited.”

For their study, Hwang and colleagues conducted research in one of the driest parts of the Atacama Desert. They collected and analyzed soil samples from three different locations – up to 205 kilometers apart. They specifically searched for bacteria and viruses. And with success. “The viruses we identify in our study are all phages,” Hwang says. These are viruses that infect bacteria. “Most infect Actinobacteria and are not very closely related to previously identified phages.”

Home

Years ago, when researchers discovered bacteria in the Atacama Desert, this did not immediately prove that these microorganisms also felt at home and thrived here. In fact, some scientists suspected that the bacteria were not part of a thriving microbial community, but had blown into the desert and were doomed to die there. Later research showed that the bacteria were not visitors, but inhabitants of the desert and that they had a great time there. But now that viruses have been discovered in the Atacama Desert, it immediately raises the question whether they too are really at home there. There can be little doubt about this, according to Hwang, because in the study she and her colleagues show that the viruses have infected bacteria. “The fact that many of these viruses interact with the microbes – which we know live in this environment and also multiply – proves that these viruses are really part of the endemic ecosystem.”

Genes

Normally, being infected by a virus is not immediately good news. Remarkably, however, some of the bacteria in the Atacama Desert may benefit from it. “We have discovered extremotolerant genes in the viral genomes,” says Hwang. These are genes that make organisms more resistant to extreme conditions, such as drought. And it is now suspected that the viruses can transfer these genes to their host – the bacteria – and thus help them survive. “We believe that the viruses play a role in spreading extremotolerant genes among microbial hosts.”

Viruses on Mars

Whether similar interactions between bacteria and viruses take place on Mars is impossible to say at this time. But it certainly doesn’t seem unthinkable. “We don’t know what life looks like on other planets,” said Hwang. “But until now, we imagined that if there were life on Mars, it would be a bit like terrestrial microbial life. However, if we are going to look for life on Mars, we should also be looking for virus-like entities, because if there has been bacteria-like life on Mars, then virus-like particles may also have been present.”

Planetary Protection

In addition, the research also has implications for planetary protection. The term refers to the fact that we must protect other, potentially habitable celestial bodies from ‘contamination’ by terrestrial microorganisms. And in this context, for example, rovers traveling to Mars are thoroughly sterilized to prevent micro-organisms from piggybacking on to Mars and outcompeting any Martian life forms there or – in the search for extraterrestrial life – at a later stage by mistake themselves for Martian life forms. since. Again, the focus is often on bacteria. But we must not erase the viruses. “It is important that we are careful not to transport biological entities to Mars,” Hwang says. “And it’s not just about organisms that can replicate themselves, such as bacteria, but also about viral particles.” Because if those virus particles manage to survive on Mars, they may also spread far away from their landing site, the researchers warn. They base themselves again on what they saw in the Atacama Desert. “We found viruses in the desert that infected bacteria and could spread over a distance of up to 200 kilometers.”

More research into the interaction between the bacteria and viruses in the extreme environment called the Atacama Desert is desperately needed. For example, it is still unclear how widespread the interaction between bacteria and viruses is in such extreme environments. Researchers also do not yet know how often the viruses gift the extremotolerant genes to their hosts. What the researchers can say for sure is that viruses have a much more complex relationship with their host than previously thought. “And probably viruses also play an important role in the survival of extreme microbiomes.” The fact that viruses lend a helping hand to bacteria on the equally extreme Mars in a similar way is an intriguing possibility that also calls for further investigation.