Oligotrophic Growth of Nitrate-Dependent Fe 2+ -Oxidising Microorganisms Under Simulated Early Martian Conditions.

Autor:	Price A; School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom., Macey MC; School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom., Pearson VK; School of Physical Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom., Schwenzer SP; School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom., Ramkissoon NK; School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom., Olsson-Francis K; School of Environment, Earth and Ecosystem Sciences, Faculty of Science, Technology, Engineering, and Mathematics, The Open University, Milton Keynes, United Kingdom.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2022 Mar 28; Vol. 13, pp. 800219. Date of Electronic Publication: 2022 Mar 28 (Print Publication: 2022).
DOI:	10.3389/fmicb.2022.800219
Abstrakt:	Nitrate-dependent Fe 2+ oxidation (NDFO) is a microbially mediated process observed in many anaerobic, low-nutrient (oligotrophic) neutral-alkaline environments on Earth, which describes oxidation of Fe 2+ to Fe 3+ in tandem with microbial nitrate reduction. Evidence suggests that similar environments existed on Mars during the Noachian epoch (4.1-3.7 Ga) and in periodic, localised environments more recently, indicating that NDFO metabolism could have played a role in a potential early martian biosphere. In this paper, three NDFO microorganisms, Acidovorax sp. strain BoFeN1, Pseudogulbenkiania sp. strain 2002 and Paracoccus sp. strain KS1, were assessed for their ability to grow oligotrophically in simulated martian brines and in a minimal medium with olivine as a solid Fe 2+ source. These simulant-derived media were developed from modelled fluids based on the geochemistry of Mars sample locations at Rocknest (contemporary Mars soil), Paso Robles (sulphur-rich soil), Haematite Slope (haematite-rich soil) and a Shergottite meteorite (common basalt). The Shergottite medium was able to support growth of all three organisms, while the contemporary Mars medium supported growth of Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002; however, growth was not accompanied by significant Fe 2+ oxidation. Each of the strains was also able to grow in oligotrophic minimal media with olivine as the sole Fe 2+ source. Biomineralised cells of Pseudogulbenkiania sp. strain 2002 were identified on the surface of the olivine, representing a potential biosignature for NDFO microorganisms in martian samples. The results suggest that NDFO microorganisms could have thrived in early martian groundwaters under oligotrophic conditions, depending on the local lithology. This can guide missions in identifying palaeoenvironments of interest for biosignature detection. Indeed, biomineralised cells identified on the olivine surface provide a previously unexplored mechanism for the preservation of morphological biosignatures in the martian geological record. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Price, Macey, Pearson, Schwenzer, Ramkissoon and Olsson-Francis.)
Databáze:	MEDLINE
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