火星条件下的细菌存活
Bacterial survival in Martian conditions
摘要：
我们简要讨论了关于地球和火星上生命起源的两个假说的可观察结果：石胚说（火星到地球或反之亦然）和来自一个独特祖先的起源，地球称为LUCA（LUCA假说）。为了测试一些类似于地球上的生命形式在火星上生存的可能性，我们设计并建造了两个火星环境模拟器，在那里用不同的细菌菌株进行实验：LISA和mini-LISA。我们的LISA环境室可以重现许多火星位置附近的温度，压力，紫外线通量和大气成分的变化。这两个模拟器都开放与其他有兴趣在类似于红色星球的情况下对多种样品（生物，矿物，电子）进行实验的实验室合作。在LISA中，我们研究了几种细菌菌株和内生孢子的存活。我们证实了紫外线是细胞死亡的主要原因。在这个意义上，无论是低温、压力、干燥还是大气变化都没有效果。我们发现一些芽孢杆菌菌株具有在火星条件下存活数小时而不被灰尘或其他屏蔽物屏蔽的特殊能力。我们还模拟了由风输送的尘埃在行星上发生的覆盖，在样品上吹了非常少量的火山灰颗粒或红色氧化铁颗粒。被这些尘埃颗粒覆盖的样本显示出很高的存活率，这表明在表面尘埃下，如果过去火星上存在生命，那么一些细菌菌落或细胞仍然存在。
英文摘要：
We shortly discuss the observable consequences of the two hypotheses about the origin of life on Earth and Mars: the Lithopanspermia (Mars to Earth or viceversa) and the origin from a unique progenitor, that for Earth is called LUCA (the LUCA hypothesis). To test the possibility that some lifeforms similar to the terrestrial ones may survive on Mars, we designed and built two simulators of Martian environments where to perform experiments with different bacterial strains: LISA and mini-LISA. Our LISA environmental chambers can reproduce the conditions of many Martian locations near the surface trough changes of temperature, pressure, UV fluence and atmospheric composition. Both simulators are open to collaboration with other laboratories interested in performing experiments on many kind of samples (biological, minerals, electronic) in situations similar to that of the red planet. Inside LISA we have studied the survival of several bacterial strains and endospores. We verified that the UV light is the major responsible of cell death. Neither the low temperature, nor the pressure, nor the desiccation or the atmospheric changes were effective in this sense. We found that some Bacillus strains have a particular capability to survive for some hours in Martian conditions without being screened by dust or other shields. We also simulated the coverage happening on a planet by dust transported by the winds, blowing on the samples a very small quantity of volcanic ash grains or red iron oxide particles. Samples covered by these dust grains have shown a high percentage of survival, indicating that under the surface dust, if life were to be present on Mars in the past, some bacteria colonies or cells could still be present.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
