CEA, CNRS, IBS, Metalloproteins Unit, Université Grenoble Alpes, 38000, Grenoble, France.
State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, 999078, PR China.
Sci Rep. 2021 Nov 2;11(1):21543. doi: 10.1038/s41598-021-00730-8.
The preservation of biosignatures on Mars is largely associated with extensive deposits of clays formed under mild early Noachian conditions (> 3.9 Ga). They were followed by widespread precipitation of acidic sulfates considered adverse for biomolecule preservation. In this paper, an exhaustive mass spectrometry investigation of ferric subsurface materials in the Rio Tinto gossan deposit (~ 25 Ma) provides evidence of well-preserved molecular biosignatures under oxidative and acidic conditions. Time of flight secondary ion mass spectrometry (ToF-SIMS) analysis shows a direct association between physical-templating biological structures and molecular biosignatures. This relation implies that the quality of molecular preservation is exceptional and provides information on microbial life formerly operating in the shallow regions of the Rio Tinto subsurface. Consequently, low-pH oxidative environments on Mars could also record molecular information about ancient life in the same way as the Noachian clay-rich deposits.
火星上生物特征的保存主要与广泛的粘土沉积有关，这些粘土是在早期诺亚纪温和条件下形成的（>39 亿年）。随后，广泛形成的酸性硫酸盐沉淀被认为不利于生物分子的保存。本文对里约廷托矿（~25 百万年）地下含铁物质进行了详尽的质谱研究，为氧化和酸性条件下保存完好的分子生物特征提供了证据。飞行时间二次离子质谱（ToF-SIMS）分析表明，物理模板生物结构与分子生物特征之间存在直接联系。这种关系意味着分子保存的质量是特殊的，并提供了有关以前在里约廷托地下浅层区域运行的微生物生命的信息。因此，火星上的低 pH 值氧化环境也可以以与富含诺亚纪粘土的沉积物相同的方式记录关于古代生命的分子信息。
