Survival of NASA-cleanroom microbial isolates under simulated space and Martian conditions | Applied and Environmental Microbiology
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Open access<br>Editor's Pick<br>Environmental Microbiology<br>Research Article<br>20 April 2026
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Survival of NASA-cleanroom microbial isolates under simulated space and Martian conditions
Authors: Atul M. Chander https://orcid.org/0000-0001-9582-6638, David J. Burr https://orcid.org/0000-0002-4208-034X, Severin Wipf https://orcid.org/0000-0003-0288-9766, Ruben Nitsche https://orcid.org/0009-0001-4379-6278, Gretchen Fujimura, Wayne Schubert https://orcid.org/0000-0002-4334-9590, Nitin K. Singh, Justin J. Bell, Alexander Brandl, Michael M. Weil, Andreas Elsaesser https://orcid.org/0000-0002-3781-8290 [email protected], Kasthuri Venkateswaran https://orcid.org/0000-0002-6742-0873 [email protected]Authors Info & Affiliations<br>https://doi.org/10.1128/aem.02065-25
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ContentsABSTRACT<br>INTRODUCTION<br>MATERIALS AND METHODS<br>RESULTS<br>DISCUSSION<br>ACKNOWLEDGMENTS<br>DATA AVAILABILITY<br>REFERENCES
ABSTRACT<br>Planetary protection hinges on understanding microbial survival following reduction procedures, the stressors of space travel, and exposure to extraterrestrial environmental conditions. This study identified 23 fungal strains isolated from NASA spacecraft assembly cleanrooms, capable of surviving ultraviolet radiation exposure. Using experimental simulation facilities, we conducted a comprehensive assessment of microbial survivability and morphology on the most resilient spacecraft-associated microorganisms. Aspergillus calidoustus demonstrated remarkable survival under simulated Martian conditions, withstanding up to 1,440 min of Martian solar irradiation, Mars atmospheric pressure and composition, and the presence of Martian regolith. Lethality only occurred under combined irradiation and cooling to −60°C (the mean Mars surface temperature), emphasizing the synergistic effect of these conditions. Furthermore, A. calidoustus survived long-duration neutron radiation exposure (replicating ionizing space radiation doses) and dry-heat microbial reduction technique (typically used for spacecraft components). This is the first study to perform an end-to-end evaluation of eukaryotic microbial survival across conditions that occur during preparation for, travel to, and robotic exploration of Mars. The experimental facilities and chronic exposure methods utilized offer a biologically meaningful model for understanding microbial risks during long-duration space missions. The capacity for fungal conidia to survive multiple space-relevant conditions suggests their potential as forward contaminants, capable of being transported to and persisting on Mars. As current spacecraft microbial reduction protocols prioritize bacterial spores, this research highlights a critical gap in planetary protection strategies. In addition to offering novel insights into microbial survival, these findings have broader implications for biocontamination within the food, pharmaceutical, and medical sectors.<br>IMPORTANCE<br>This study reveals that conidia of the fungus Aspergillus calidoustus, which was isolated from spacecraft assembly cleanrooms, can survive simulated space-relevant stressors like ultraviolet irradiation, Martian cold atmospheric pressure, regolith exposure, ionizing radiation, and specific doses of recommended dry-heat microbial reduction method for spacecraft. Such...