A team of German researchers has now developed a streamlined method for inducing chemotactic motility in microbes, potentially aiding space missions in detecting life beyond Earth. Their findings were recently published in Frontiers in Astronomy and Space Sciences.
"We tested three types of microbes - two bacteria and one type of archaea - and found that they all moved toward a chemical called L-serine," explained Max Riekeles, a researcher at the Technical University of Berlin. "This movement, known as chemotaxis, could be a strong indicator of life and could guide future space missions looking for living organisms on Mars or other planets."
"Bacteria and archaea are two of the oldest forms of life on Earth, but they move in different ways and evolved motility systems independently from each other," Riekeles noted. "By testing both groups, we can make life detection methods more reliable for space missions."
L-serine, the amino acid used in the study, has been widely recognized as a chemotactic agent across various species and is believed to exist on Mars. If Martian life shares biochemical similarities with terrestrial life, L-serine could potentially attract Martian microbes.
The researchers employed a straightforward technique that enhances feasibility for space missions. Instead of relying on sophisticated instrumentation, they used a slide with two chambers separated by a thin membrane. Microbes were placed in one chamber, while L-serine was introduced into the other. "If the microbes are alive and able to move, they swim toward the L-serine through the membrane," Riekeles explained. "This method is easy, affordable, and doesn't require powerful computers to analyze the results."
However, adapting this method for space missions requires overcoming several challenges. The system must be miniaturized, robust enough to withstand the conditions of space travel, and fully automated to function without human intervention.
If these obstacles are addressed, microbial motility could provide a powerful tool for detecting extraterrestrial life, particularly in environments such as the subsurface ocean of Jupiter's moon Europa. "This approach could make life detection cheaper and faster, helping future missions achieve more with fewer resources," Riekeles concluded. "It could be a simple way to look for life on future Mars missions and a useful addition for direct motility observation techniques."