An international team of radiologists, biologists and infectious disease experts has identified four types of bacteria capable of surviving exposure to the hostile Martian environment. In their study, published in the journal Astrobiology, the team exposed four human-infecting bacteria to Martian-like conditions.
Over the past several years, microbiologists have discovered that certain types of bacteria are capable of surviving the most hostile environments on Earth and in space. Bacteria have been found to thrive in places on Earth with unusually high levels of radiation, salt, extreme temperatures and almost no water. One species was found to live on the exterior of the space station and other species could grow on meteorite material.
Such findings have led to concerns about the safety of astronauts traveling to places like Mars — bacteria from Earth carried by astronauts or the equipment they bring could lead to illness or death. In this new study, the research team wondered about the possibility of bacteria from Earth surviving on Mars.
To test the possibility, the researchers created a Mars-like environment in a box in their lab, with a regolith stand-in, cold temperatures, an oxygen-free atmosphere and exposure to radiation. They then added four types of bacteria one at a time: Serratia marcescens, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Burkholderia cepacia. All four are harmful to humans.
The team first tested how each bacterial species responded individually to each of the simulated conditions. They then subjected all four types to all conditions simultaneously. They found varying responses – b. Sebacean, for example, could not grow in sodium-perchlorate-rich soil, which is possible on Mars. Also, dramatically reducing the amount of water in the environment reduced survival.
But they also found that all four survived somewhat when exposed to everything Mars threw at them — three of them survived 21 days, and one of them, B. Aeruginosa seemed to multiply and thrive.
The research team concludes that bacteria inadvertently carried to Mars could pose a health risk to astronauts, especially since bacteria are better suited to survive in harsh conditions.
Further information: Tommaso Zaccaria et al, Survival of Environmentally Derived Opportunistic Bacterial Pathogens on Martian Conditions: Are Human Expeditions to Mars Concerned?, Astrobiology (2024). DOI: 10.1089/ast.2023.0057
Astronomy