1 Department of Bioscience, Aarhus University , Aarhus, Denmark .
2 Department of Chemistry, Aarhus University , Aarhus, Denmark .
Astrobiology. 2019 Apr;19(4):497-505. doi: 10.1089/ast.2018.1856. Epub 2018 Nov 8.
Numerous studies have demonstrated that the martian surface environment is hostile to life because of its rough radiation climate and the reactive chemistry of the regolith. Physical processes such as erosion and transport of mineral particles by wind-driven saltation have hitherto not been considered as a life hazard. We report a series of experiments where bacterial endospores (spores of Bacillus subtilis) were exposed to a simulated saltating martian environment. We observed that 50% of the spores that are known to be highly resistant to radiation and oxidizing chemicals were destroyed by saltation-mediated abrasion within one minute. Scanning electron micrographs show that the spores were not only damaged by abrasion but were eradicated during the saltation process. We suggest that abrasion mediated by wind-driven saltation should be included as a factor that defines the habitability of the martian surface environment. The process may efficiently protect the martian surface from forward contamination with terrestrial microbial life-forms. Abrasion mediated by wind-driven saltation should also be considered as a major challenge to indigenous martian surface life if it exists/existed.
许多研究表明，由于火星表面环境辐射剧烈且土壤具有较强的反应性，因此对生命而言非常恶劣。到目前为止，风成跃移过程中矿物质颗粒的侵蚀和输运等物理过程尚未被认为是生命危害。我们报告了一系列实验，其中将细菌芽孢（枯草芽孢杆菌的芽孢）暴露在模拟的火星跃移环境中。我们观察到，已知对辐射和氧化化学品具有高度抗性的芽孢中，有 50%在一分钟内被跃移介导的磨蚀破坏。扫描电子显微镜图像显示，芽孢不仅受到磨蚀的破坏，而且在跃移过程中被彻底消灭。我们认为，应该将风成跃移介导的磨蚀作为定义火星表面环境可居住性的一个因素。该过程可以有效地保护火星表面免受地球微生物生命形式的向前污染。如果火星表面存在土著生命，那么风成跃移介导的磨蚀也应该被视为对其的主要挑战。
