To find life on Mars, make microbes move

To find life on Mars, make microbes move

By Gayoung Lee Edited by Lee Billings

The last advance in the search for extraterrestrial life could come from the “minors” of swimming microbes: unicellular microscopic organisms that abound in almost every corner and cracks of the earth.

The microbes are found throughout the biosphere of our planet because many of them can flourish in very hard conditions that apparently prevent greater and complex life forms. And that remarkable resistance is the reason why astrobiologists are so interested in studying them. If, for example, microbes can prosper in a buried lake under the polar ice layer of the southern Earth, perhaps there could be similar organisms in very similar extraterrestrial environments, such as the mysterious ocean covered with ice of Jupiter’s moon or the regions in advance of Mars of the Subsurfaces of Mars. . But the trick is not simply showing that alien life could exist in such places but rather confirm That does so, which requires detecting your presence in the first place. Most interplanetary life detection experiments have involved the search for chemical, biosignant tracers, which the microbes of another world could create in their environments as a byproduct of their metabolism. Now, however, a new approach based on self -guided movement or microbes motility can be in scope.

Historically, microbial motility tests have been a expensive task that requires a lot of time, badly suitable for incorporation into robotic space missions. That has led to a team of German astrobiologists to devise a simpler and more profitable way to verify motility, an approach they have detailed in a study published on February 6 in the magazine. Borders in Astronomy and Space Sciences.

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In their study, researchers focused on three types of microbes:Bacillus subtilis, Pseudoalteromonas harylapanktis and Halotax volcanii—All of which are extremesphils or known organisms that can survive extreme temperatures, pressures or chemical conditions. Your experiment was simple: could you incite microbes to swim towards a source of nutrients in a detectable and repeatable way? To do this, they placed drops of water full of microbes in a partition of a microscopic slide of two cameras. On the other hand, there was an aqueous solution that was rich with L-Serine, an amino acid that is critical for protein synthesis and cell proliferation. When they tested each type of microbe in separate experimental races of three hours, researchers could see that the three species become mobile and migratory: the microbes swam from their initial chamber to form “blobs” inside the camera with L-Serine. This trend of the organism is derived from or far from the presence of certain chemicals is called “chemotaxis”.

In the case of organisms used in this experiment, “the idea of ​​chemotaxis is that microbes may feel [and move to] Molecules that could be useful for them, especially for metabolism, “explains the main author of the Max Riekeles study, a PH.D. Student of the Technical University of Berlin.” With our specific configuration, we wanted to do the visual and computational aspects [of studying chemotaxis] simpler “.

The problem with past chemiotaxis -based methods to boost and monitor microbial motility is that “it is difficult to establish chemical gradients that are reliable, stable and predictable,” says Christian LindensMh NASA. In addition, “observing motility is difficult because microscopes have a small field of vision” and microbes can move to Other completely external reasonssuch as thermal mixture and inertial drift. “It is very complicated, as if you were running this microscopic zoo,” he adds.

A gel membrane that separated the two cameras from the new experiment was crucial to minimize such difficulties by largely reducing the microbes movement options. This semipermeable gel essentially acted as a unidirectional barrier that allowed the organisms on one side to pass relatively fast, while also slowed the filtration of L-Serine on the other side, thus maintaining the motivation of the microbes to move. The configuration was “a good option,” says Jay Nadeau, an astrobiologist and physics professor at Portland State University, because he greatly facilitated the motility of the microbes, everything that the barrier maintained the microbes in the L-Serine. side once they entered.

Such technical advances could be very beneficial for future space missions of life search, says Nadeau and Lindensmith, who were previously Riekeles colleagues but were not involved with the new study. “One of the real problems to do something like this in another world, especially one that will be very cold, such as Europe, is: what happens if those happen if those [alien] Do organisms swim very, very slowly? Nadeau explains. “Well, in that case, you may have to leave them for a week or more and then return.”

Using the new method, scientists could simply verify any microbe in the chamber full of nutrients instead of constantly monitoring the system for trashing microbes remarkably. “So that part is easy,” says Lindensmith. “The difficult part is to discover what to put on the other side as a bait.” Although the life of the earth’s own harvest can love L-Serine and other similarly fundamental foods, there is no guarantee that such substances are attractive to alien organisms with a different biochemistry.

Even assuming that the nutrient menu of life is identical throughout the cosmos, however, other obstacles remain before this method can manifest in some type of measurement device in a real interplanetary astrobiology mission. For Riekeles, the next challenge is not only the need to even more refine this technique with new and more extensive experiments, but also the question of “engineering and test with different types of microbes” and amino acids.

“One of the objectives [of astrobiology] It is going to [other worlds] And looking for microorganisms, but in the meantime there is so much that we can do on earth that they will give us massive ideas, ”says Nadeau. And this new method for microbial classification is a great example of simple but crucial work for future efforts to build.

“You don’t know what will be out there [in space]”, Says Lindensmith, so diversifying his tools and techniques to analyze life here on our own planet is an important first step.” We have to be able to do all that kind of thing on earth before we can do it significantly in others planets “.