Scientists have studied microbial movement as a potential biosignature for detecting life on Mars and beyond, providing a faster and more cost-effective way to detect life on Mars and beyond. The search for life in outer space is one of mankind's greatest undertakings.One approach is to detect motile microorganisms capable of independent movement - an ability that strongly suggests the presence of life. When a chemical stimulus triggers movement and an organism responds accordingly, the phenomenon is called chemotaxis.
Now, researchers in Germany have developed a new, simplified method for inducing chemotactic movements in some of the smallest life forms on Earth. Their research results were published in Frontiers in Astronomy and Space Sciences.
Max Riekeles, a researcher at TU Berlin, said: "We tested three microorganisms - two bacteria and one archaea - and found that they all moved towards a chemical called L-serine. This movement, known as chemotaxis, could be a strong indicator of life and could provide guidance for future space missions looking for organisms on Mars or other planets."
The species in the study were chosen for their ability to survive in extreme environments. The highly motile Bacillus subtilis survives in extreme conditions in the form of spores, which can withstand temperatures up to 100°C. Pseudoalteromonashaloplanktis was isolated from Antarctic waters and is good at growing in cold environments of -2.5° to 29°C. The archaea Haloferax volcanii (H. volcanii) is similar to bacteria but genetically different. Its natural habitat includes the Dead Sea and other high-salinity environments, so it is also well adapted to extreme conditions.
"Bacteria and archaea are two of the oldest life forms on Earth, but they move in different ways and have evolved independent locomotion systems," Riekeles explains. "By testing these two types of life, we can make life detection methods more reliable in space missions."
The amino acid L-serine, which the researchers used to get these species moving, has previously been shown to trigger chemotaxis in a variety of species across all areas of life. This material is also believed to exist on Mars. If life on Mars has similar biochemistry to life on Earth, L-serine has the potential to attract potential Martian microorganisms.
Research results show that L-serine has an attractive effect on these three types of microorganisms. "The use of Haloferax volcanii in particular expands the range of potential life forms that can be detected by chemotaxis-based methods, even though some archaea are known to possess chemotaxis systems," Riekeles explained. "Because H. volcanii thrives in extremely salty environments, it could serve as a good model for the types of life we might find on Mars."
Researchers used a simplified approach that could determine whether future space missions are feasible. Instead of complicated equipment, they used a glass slide with two chambers separated by a membrane. Microorganisms were placed on one side and the chemical L-serine was added to the other. "If the microorganisms are alive and able to move, they will swim through the membrane toward L-serine," Riekeles explains. "This method is simple, cost-effective, and does not require powerful computers to analyze the results."
However, researchers say some adjustments to the process will be needed for this approach to work on space missions. Two of the adjustments are: the equipment needs to be smaller and more rugged to survive the harsh conditions of space travel; and the system needs to work automatically without human intervention.
Once these difficulties are overcome, microbial movements could help detect possible microbes in outer space, such as in the oceans of Jupiter's moon Europa. Riekeles concluded: "This method could make life detection cheaper and faster, helping future missions achieve more with fewer resources. This could be a simple way to search for life on future Mars missions and a useful complement to direct motion observation techniques."
Compiled from /ScitechDaily