Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes-Experiment PROTECT of the EXPOSE-E Mission
Resistance of Bacterial Endospores to Outer Space for Planetary Protection Purposes-Experiment PROTECT of the EXPOSE-E Mission
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DOI：
10.1089/ast.2011.0737
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发表时间：
2012-05-01
期刊：
影响因子：
4.2
通讯作者：
Venkateswaran, Kasthuri J.
中科院分区：
文献类型：
--
作者：
Horneck, Gerda;Moeller, Ralf;Venkateswaran, Kasthuri J.
在行星保护的背景下，形成孢子的细菌特别值得关注，因为它们坚韧的内生孢子可以经受某些灭菌程序以及外层空间或行星表面的恶劣环境。为了测试它们在假设的火星任务中的耐寒性，在国际空间站的EXPOSE-E任务中，在实验PROTECT中，枯草芽孢杆菌168和短芽孢杆菌SAFR-032的孢子暴露在选定的空间参数中1.5年。“火星之旅”孢子被安装在符合航天器要求的铝券上，作为干燥层，它们经历了空间真空、宇宙和地外太阳辐射以及温度波动，而“留在火星上”孢子则受到模拟火星环境的影响，包括大气压力和成分、紫外线和宇宙辐射。回收后测定两种方法的孢子存活率。结果清楚地表明，太阳地外紫外线辐射（λ >= 110 nm）和火星紫外线光谱（λ >= 200 nm）是应用的最有害因素；在一些样品中，只有少数幸存者从单层暴露的孢子中恢复。多层孢子存活的好几个数量级。“火星之旅”或“留在火星上”孢子遇到的所有其他环境参数对孢子几乎没有伤害，孢子的存活率约为50%或更高。这些数据表明，如果不受太阳辐射的影响，孢子在火星任务中存活的几率很高。这些结果将对行星保护的考虑产生影响。
Spore-forming bacteria are of particular concern in the context of planetary protection because their tough endospores may withstand certain sterilization procedures as well as the harsh environments of outer space or planetary surfaces. To test their hardiness on a hypothetical mission to Mars, spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space in the experiment PROTECT during the EXPOSE-E mission on board the International Space Station. Mounted as dry layers on spacecraft-qualified aluminum coupons, the "trip to Mars" spores experienced space vacuum, cosmic and extraterrestrial solar radiation, and temperature fluctuations, whereas the "stay on Mars" spores were subjected to a simulated martian environment that included atmospheric pressure and composition, and UV and cosmic radiation. The survival of spores from both assays was determined after retrieval. It was clearly shown that solar extraterrestrial UV radiation (lambda >= 110 nm) as well as the martian UV spectrum (lambda >= 200 nm) was the most deleterious factor applied; in some samples only a few survivors were recovered from spores exposed in monolayers. Spores in multilayers survived better by several orders of magnitude. All other environmental parameters encountered by the "trip to Mars" or "stay on Mars" spores did little harm to the spores, which showed about 50% survival or more. The data demonstrate the high chance of survival of spores on a Mars mission, if protected against solar irradiation. These results will have implications for planetary protection considerations.