Efforts to find ET gains momentum with new technique that detects microbial movement

Efforts to find ET gains momentum with new technique that detects microbial movement
by Clarence Oxford
Berlin, Germany (SPX) Feb 10, 2025

The search for life beyond Earth is among the most ambitious scientific quests. One promising method is to locate motile microorganisms, capable of self-propelled movement, which serves as a strong biological indicator. If such movement is driven by a specific chemical, it is referred to as chemotaxis.

A team of German researchers has now introduced a new and simplified technique to stimulate chemotactic motion in some of Earth's tiniest organisms. Their findings have been published in Frontiers in Astronomy and Space Sciences.

"We examined three different microbes-two bacterial species and one archaeon-and discovered that all of them were drawn toward L-serine," explained Max Riekeles, a researcher at the Technical University of Berlin. "This chemotactic behavior could serve as a strong indicator of life and inform future space missions searching for microbial organisms on Mars or other celestial bodies."

Survival in Extreme Conditions

The microorganisms selected for the study were chosen for their resilience in harsh environments. The highly motile Bacillus subtilis, when in its spore form, can endure extreme conditions, surviving temperatures as high as 100C. Another species, Pseudoalteromonas haloplanktis, thrives in frigid waters, capable of growing in temperatures ranging from -2.5C to 29C. Meanwhile, the archaeon Haloferax volcanii, which shares similarities with bacteria but has distinct genetic differences, naturally inhabits high-salinity environments such as the Dead Sea.

"Bacteria and archaea are among the most ancient life forms on Earth, yet they exhibit distinct motility mechanisms that evolved independently," Riekeles noted. "By including both groups in our study, we enhance the reliability of life-detection methods for space exploration."

L-serine, the amino acid employed in the study, has previously been recognized as a chemotactic trigger across various life forms. Furthermore, its presence is suspected on Mars. If Martian life shares biochemical similarities with terrestrial organisms, L-serine could be an effective attractant for potential Martian microbes.

Detecting Motion in Microbes

The study revealed that L-serine successfully attracted all three tested species. "Using H. volcanii in this research expands the range of life forms that could be identified through chemotaxis-based detection, particularly since archaea are known to possess chemotactic systems," Riekeles elaborated. "Given that H. volcanii thrives in highly saline conditions, it could serve as an excellent model for potential Martian life."

The researchers developed a simplified technique that enhances feasibility for space missions. Instead of requiring intricate laboratory instruments, their method relies on a slide featuring two chambers separated by a thin membrane. Microbes are placed on one side while L-serine is introduced to the other. "If the microbes are alive and motile, they swim through the membrane toward the L-serine," Riekeles explained. "This approach is cost-effective, straightforward, and does not demand extensive computing power for analysis."

However, to implement this method in a space mission, certain refinements are necessary. The researchers highlighted the need for compact and resilient equipment capable of withstanding the rigors of space travel, as well as automation to function without human supervision.

If these challenges are addressed, microbial movement could aid in identifying extraterrestrial organisms, such as those potentially inhabiting Jupiter's moon Europa. "This approach could make life detection more efficient and cost-effective, enabling future missions to maximize scientific returns with limited resources," Riekeles concluded. "It represents a practical tool for upcoming Mars missions and complements other direct motility observation techniques."

Research Report:Application of chemotactic behavior for life detection