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Abstract EANA2026-27 |
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Bacillus subtilis under simulated Martian conditions: New insights into the upgraded MARTE simulation chamber for in-depth studies of biological exposure to a Mars-like atmosphere.
The remarkable resilience and widespread distribution of the Gram-positive bacterium Bacillus subtilis make it a highly suitable model for investigating microbial habitability under Martian conditions. Its spores are known to withstand a wide range of extreme stresses, including severe desiccation, intense UV and ionizing radiation, high-vacuum environments, and broad temperature fluctuations, establishing B. subtilis as a key model organism in space microbiology (1). However, considerably less attention has been given to the response of vegetative cells under extreme environments such as the Martian surface.
We designed, constructed, and implemented a real-time liquid sampling system within the MARTE chamber (2), a high-vacuum system that reproduces key environmental parameters such as pressure, surface temperature, atmospheric composition and radiation, enabling the extraction of a defined fraction of the culture without opening the chamber or compromising vacuum conditions. This setup allows for extended exposure experiments while ensuring continuous monitoring of culture dynamics.
Using this system, we exposed B. subtilis to a simulated Martian atmosphere over multiple sols and performed proteomic analysis. Despite cell viability being decreased significantly and a marked reduction in overall protein synthesis under these conditions, proteins associated with carbohydrate metabolism, sporulation, stress-response pathways and oxidative stress protection were detected. Collectively, these results demonstrate that B. subtilis can extensively reorganize its cellular machinery to enhance adaptation and survival under Mars-like environmental conditions, highlighting the robustness and plasticity of its physiological responses.
(1) Muñoz-Hisado, V., Ruiz-Blas, F., Sobrado, J. M., Garcia-Lopez, E., Martinez-Alonso, E., Alcázar, A., & Cid, C. (2023). Bacterial molecular machinery in the Martian cryosphere conditions. Frontiers In Microbiology, 14, 1176582. https://doi.org/10.3389/fmicb.2023.1176582
(2) Sobrado, J. M., Martín-Soler, J., & Martín-Gago, J. A. (2014). Mimicking Mars: A vacuum simulation chamber for testing environmental instrumentation for Mars exploration. Review Of Scientific Instruments, 85(3), 035111. https://doi.org/10.1063/1.4868592