Abstract EANA2024-129

Chemolithoautotrophic organisms use atmospheric CO2 as a carbon source and redox-alter minerals by oxidizing inorganic compounds (such as iron, sulfur, and other reduced inorganic sulfur compounds). The extremely thermoacidophilic archaeon Acidianus manzaensis, from the order Sulfolobales, was isolated from a hot fumarole in Manza, Japan. It thrives at high temperatures and low pH, and tolerates high concentrations of heavy metals. Moreover, its genome has been fully sequenced, facilitating molecular studies on its metabolic capacity. Owing to the similarity between the early planetary stages of Earth and Mars, including the presence of liquid water and volcanic activity on the surface and an atmosphere rich in CO2, their metabolic pathways make these microorganisms excellent candidates for astrobiological research. A. manzaensis was cultivated on the Mars analog material ESA01-E, which is known for its physicochemical similarity to Martian basalt. A dehydration experiment has been conducted over a period of one month to test its survivability under desiccated conditions. In this process, concentrated cell pellets of A. manzaensis have been deposited into metal hardware exposure wells to monitor cell survival upon recovery of dried pellets in a heterotrophic medium, following the protocol described by Kölbl et al. (2020) [1]. Furthermore, metabolomic analysis of desiccated cells has been conducted using ultra-high-performance liquid chromatography coupled to high-resolution Quadrupole / Time of Flight Mass Spectrometry (UHPLC-Q/TOF MS). The target molecules in this study are thiophene-bearing quinones, with thiophene headgroups and quinone tails. They serve as respiratory electron carriers in Sulfolobales and are chemotaxonomic markers of archaeal cells that mediate metal redox processes [2]. These molecules are of particular interest because of the detection of sulfur compounds, such as ethanethiol and thiophene, at Gale Crater on Mars [3]. It has been proposed that thiophene-bearing quinones could serve as biomarkers for the detection of life beyond Earth, owing to their longevity and stability over geological time periods [4]. However, exposure to Mars-like conditions likely alters the molecular signatures of the thiophene headgroups over time. Therefore, in addition to desiccation, an exposure experiment under Mars-like conditions can further clarify the role of these molecules as potential biosignatures for the search for life on Mars and other celestial bodies. Our experimental approach may provide a method for effective analytical investigations to evaluate the potential biogenicity of samples returned from Mars.

[1] Kölbl, D., Blazevic, A., Albu, M., Fasching, C., & Milojevic, T., Frontiers in Astronomy and Space Sciences, 7, 41 (2020)

[2] Elling, F. J., Becker, K. W., Könneke, M., Schröder, J. M., Kellermann, M. Y., Thomm, M. & Hinrichs, K. U., Environmental microbiology, 18 (2), 692-707 (2016)

[3] Millan, M., Williams, A. J., McAdam, A. C., Eigenbrode, J. L., Steele, A., Freissinet, C. & Mahaffy, P. R., Journal of Geophysical Research: Planets, 127, 11 (2022)

[4] Heinz, J., and Schulze-Makuch, D., Astrobiology, 20 (4), 552-561 (2020)