Oligotrophic Growth of Nitrate-Dependent Fe2+-Oxidising Microorganisms Under Simulated Early Martian Conditions

作者：Alex Price, Michael C. Macey, V. K. Pearson, S. P. Schwenzer, Nisha K. Ramkissoon, Karen Olsson‐Francis · 发表于：Frontiers in Microbiology · 年份：2022 · DOI：10.3389/fmicb.2022.800219 · 被引用次数：14 · 研究领域：Planetary Science and Exploration、Paleontology and Stratigraphy of Fossils、Geochemistry and Elemental Analysis

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...