Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain.
Astrobiology. 2011 Dec;11(10):969-96. doi: 10.1089/ast.2011.0654. Epub 2011 Dec 9.
The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg(-1)) and perchlorate (41.13 μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g(-1)) or formate (76.06 μg g(-1)) as electron donors, and sulfate (15875 μg g(-1)), nitrate (13490 μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.
阿塔卡马沙漠长期以来一直被认为是测试行星探测仪器的良好火星模拟地，但很少有关于其富盐地下地质微生物学的数据（如果有的话）。我们于 2009 年 7 月在格兰德盐沼（智利阿塔卡马沙漠）旁边进行了一项火星模拟钻探活动，对来自 5 米深处的多个岩芯和粉末样本进行了现场分析，使用了 LDChip300（一种含有 300 种抗体的生命探测器芯片）。在这里，我们发现了一个与富含盐的地下微生物栖息地相关的高盐度地下微生物栖息地，该栖息地与含有卤盐、硝酸盐和高氯酸盐的盐有关，深度为 2 米。LDChip300 从不到 0.5 克的地面岩芯样本分析中检测到细菌、古菌和其他生物材料（DNA、胞外多糖、一些肽）。这些结果得到了现场寡核苷酸微阵列杂交的支持，并最终通过分子系统发育分析和在实验室中直接观察结合到卤盐晶体上的微生物细胞得到证实。地球化学分析表明，该栖息地有丰富的吸湿性盐，如卤盐（高达 260 克/千克）和高氯酸盐（最高 41.13μg/g），这些盐在低相对湿度下会发生潮解。薄的液态水膜将允许微生物通过利用检测到的有机酸盐（如乙酸盐 19.14μg/g）或甲酸盐（76.06μg/g）作为电子供体，以及硫酸盐（15875μg/g）、硝酸盐（13490μg/g）或高氯酸盐作为电子受体来增殖。我们的结果与在火星上发现类似的吸湿性盐和可能的潮解过程相关，并为地下火星生物群的搜索开辟了新的策略。我们的 LDChip300 表现验证了这项技术在行星探索中的应用，特别是在火星生命的搜索方面。
