Extraterrestrial environments influence the biochemistry of organisms through a variety of factors, including high levels of radiation and vacuum, temperature extremes and a lack of water and nutrients. A wide variety of terrestrial microorganisms, including those counted amongst the most ancient inhabitants of Earth, can cope with high levels of salinity, extreme temperatures, desiccation and high levels of radiation. Key among these are the haloarchaea, considered particularly relevant for astrobiological studies due to their ability to thrive in hypersaline environments. In this study, a novel haloarchaea isolated from Urmia Salt Lake, Iran, Halovarius luteus strain DA50^T, was exposed to varying levels of simulated extraterrestrial conditions and compared to that of the bacteria Bacillus atrophaeus. Bacillus atrophaeus was selected for comparison due to its well-described resistance to extreme conditions and its ability to produce strong spore structures. Thin films were produced to investigate viability without the protective influence of cell multi-layers. Late exponential phase cultures of Hvr. luteus and B. atrophaeus were placed in brine and phosphate buffered saline media, respectively. The solutions were allowed to evaporate and cells were encapsulated and exposed to radiation, desiccation and vacuum conditions, and their post-exposure viability was studied by the Most Probable Number method. The protein profile using High Performance Liquid Chromatography and Matrix Assisted Laser Desorption/Ionization bench top reflector time-of-flight are explored after vacuum and UV-radiation exposure. Results showed that the change in viability of the spore-forming bacteria B. atrophaeus was only minor whereas Hvr. luteus demonstrated a range of viability under different conditions. At the peak radiation flux of 10⁵ J/m² under nitrogen flow and after two weeks of desiccation, Hvr. luteus demonstrated the greatest decrease in viability. This study further expands our understanding of the boundary conditions of astrobiologically relevant organisms in the harsh space environment.

地外环境通过多种因素影响生物体的生物化学，包括高水平的辐射和真空、极端温度以及缺乏水和营养物质。各种各样的陆地微生物，包括地球上最古老的居民，可以应对高盐度、极端温度、干燥和高辐射。其中关键的是盐古菌，由于它们能够在高盐度环境中繁衍生息，因此被认为与天体生物学研究特别相关。在这项研究中，从伊朗乌尔米亚盐湖分离出一种新型盐古菌，即Halovarius uteus菌株 DA50 ^T，将其暴露于不同水平的模拟外星条件下，并与萎缩芽孢杆菌进行比较。选择萎缩芽孢杆菌进行比较是因为其对极端条件的良好抵抗力以及产生强大孢子结构的能力。制作薄膜以研究活力，而不受细胞多层的保护影响。 Hvr的指数期晚期培养物。将藤黄体和萎缩芽孢杆菌分别置于盐水和磷酸盐缓冲盐介质中。让溶液蒸发，将细胞封装并暴露于辐射、干燥和真空条件下，并通过最可能数方法研究其暴露后的活力。在真空和紫外线辐射暴露后，使用高效液相色谱法和基质辅助激光解吸/电离台式反射器飞行时间来探索蛋白质谱。结果表明，芽孢杆菌萎缩芽孢杆菌的活力变化很小，而Hvr。 uteus在不同条件下表现出一系列的生存能力。在氮气流下和干燥两周后，峰值辐射通量为 10 ⁵  J/m ^2时， Hvr。藤黄体的活力下降幅度最大。这项研究进一步扩大了我们对恶劣太空环境中天体生物学相关生物体边界条件的理解。