The difficult-to-detect "swimming" of microorganisms is actually the "new key" to exploring extraterrestrial life?

Author: Huang Xianghong Duan Yuechu

In the vast universe, human beings have never stopped exploring other forms of life. This exploration not only carries curiosity about the unknown, but also contains a profound pursuit of the essence and origin of life. Does extraterrestrial life exist? In what form does it exist? In what environment will it live? These questions have always lingered in the minds of scientists and have become a powerful driving force for the continuous advancement of astrobiology research. Recently, a research result on the "swimming" of microorganisms has brought us new hope and possibility to unveil the mystery of extraterrestrial life.

On February 6, a team of German astrobiologists published an innovative research result in the journal Frontiers in Astronomy and Space Science. They proposed a new, simpler and more cost-effective method for detecting the activity of microorganisms, which may provide key technical support for future extraterrestrial life detection missions. Historically, microbial dynamics testing has always been a difficult task, not only costly, but also time-consuming and labor-intensive, making it difficult to apply to robotic space missions. The research results of the German astrobiologist team are undoubtedly a major breakthrough in this difficult problem.

In this study, the researchers focused on three special microorganisms - Bacillus subtilis, Pseudoplankton Proteomonas and Volcani algae. These microorganisms are "extremists" with the extraordinary ability to survive under extreme temperature, pressure or chemical conditions. Their ability to thrive in various harsh environments on Earth has convinced astrobiologists that they may provide important clues for the search for extraterrestrial life. After all, if these microorganisms can survive in the extreme environments of the Earth, then similar life forms are likely to exist in seemingly similar alien environments in the universe.

The researchers designed a simple yet ingenious experiment. They placed a water droplet filled with microorganisms on one partition of a two-chamber microscope slide and placed an aqueous solution rich in L-serine on the other side. L-serine is an amino acid that is essential for protein synthesis and cell proliferation. Over the next three hours of separate experiments, the researchers observed an exciting phenomenon: All three microorganisms became active and began to migrate, swimming from the initial chamber to the side containing L-serine, forming a "patch" with L-serine. This tendency of organisms to drift toward or away from specific chemicals is called "chemotaxis."

"In the organisms used in the experiment, the concept of chemotaxis is the ability of microorganisms to sense and move to molecules that may be useful to them, especially in terms of metabolism," explains Max Rickles, lead author of the study and doctoral student at the Technical University of Berlin. "With their specific setup, they aimed to make it much simpler to study the visual and computational aspects of chemotaxis. This innovative experimental design significantly reduces the difficulties that previous chemotaxis-based methods faced when cuing and monitoring microbial movements."

Christian Lindensmith, an astrobiologist at NASA's Jet Propulsion Laboratory, pointed out that in the past, methods based on chemotaxis had many problems, such as the difficulty in establishing reliable, stable and predictable chemical gradients, and it was also difficult to observe the movement of microorganisms because the field of view of the microscope was very small, and the movement of microorganisms could also be affected by external factors such as thermal mixing and inertial drift, just like managing a microscopic zoo. In this new experiment, the gel membrane separating the two chambers played a key role. This semipermeable gel actually acts as a one-way barrier, which allows organisms on one side to pass relatively quickly while slowing the penetration of L-serine to the other side, thereby maintaining the motivation of the microorganisms to move. Jay Nadeau, an astrobiologist and professor of physics at Portland State University, also said that this setting is a "good choice" because it makes it easier to identify the activities of microorganisms, especially because the barrier can retain them when the microorganisms enter the L-serine side.

Both Nadeau and Lindensmith believe that these technological advances could be very beneficial for future space exploration missions. When exploring very cold planets like Europa, a real question is: What if alien life swims very, very slowly? In this case, using traditional methods may require constantly monitoring the system for obvious microbial reproduction, which is difficult and time-consuming. With this new method, scientists only need to check the nutrient tank for microorganisms to determine whether there are signs of life activity.

However, there are still many challenges for this method to be truly applied in interplanetary astrobiology missions. First, while native organisms on Earth may like L-serine and other similar basic foods, there is no guarantee that these substances will attract alien organisms with different biochemical characteristics. Therefore, figuring out what to put as bait on the other side becomes a difficult problem that needs to be solved urgently. Second, even assuming that the nutritional menu of life in the universe is the same, before this method can be applied to actual measurement equipment, the technology needs to be further refined through new and more extensive experiments, and it needs to be engineered and tested with different types of microorganisms and amino acids.

Despite the challenges, this research has undoubtedly opened up a new path for the exploration of extraterrestrial life. It allows us to see the great potential of microorganisms in astrobiology research and makes us more excited about future space exploration. As Nadeau said: "One of the goals of (astrobiology) is to go to (other worlds) to find microorganisms, but in the meantime, there are many things we can do on Earth that will give us a lot of insights." This new method for detecting microorganisms is a good example of simple but critical work, providing an important reference for future efforts to explore extraterrestrial life.

Lynden Smith also emphasized: "You don't know what's going on out there (in space). Therefore, diversifying your tools and techniques to observe life on our own planet is an important first step. We must be able to do all these things on Earth before we can do meaningful work on other planets." With the continuous advancement of science and technology, we have reason to believe that in the near future, mankind will be able to uncover the mystery of extraterrestrial life and achieve this great and challenging scientific goal.

In this journey of exploring the mysteries of life in the universe, the "swimming" of microorganisms may be just a small clue, but it may lead us to a whole new world, a new field of cosmic life full of infinite possibilities. Let us look forward to scientists making more breakthroughs in future research and bringing more surprises to human cognition and understanding of the universe.

Reference: Could tiny swimming microbes help us unlock the mysteries of extraterrestrial life? | Frontiers in Astronomy and Space Science