Natural Pyrrhotite as a Catalyst in Prebiotic  Chemical Evolution

Aldecoa, Alejandra López Ibáñez De; Roldán, Francisco Velasco; Menor‐Salván, César

doi:10.3390/life3030502

Cited by 9 publications

(7 citation statements)

References 42 publications

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“…While XRD analyses did not identify Fe 1– x S produced during abiotic reduction of FeS 2 reduction by H 2 , it was still the favored secondary mineral to form on the surface of FeS 2 based on thermodynamic calculations and observations from studies conducted at higher temperature ( Truche et al, 2010 ). Thus, the solubility of Fe 1– x S was examined to identify its plausibility as a source of soluble Fe and S. Specimen Fe 1– x S obtained from Aymar quarry, Gualba mines, Gualba, Montseny, Barcelona Spain, which has previously been shown to be of high purity ( de Aldecoa et al, 2013 ), was used in experiments. XRD of the mineral indicated that the only FeS phase present was Fe 1– x S (∼80%) with the balance as quartz ( Supplementary Figure 1D ).…”

Section: Resultsmentioning

confidence: 99%

Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction

et al. 2022

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Pyrite (FeS2) has a very low solubility and therefore has historically been considered a sink for iron (Fe) and sulfur (S) and unavailable to biology in the absence of oxygen and oxidative weathering. Anaerobic methanogens were recently shown to reduce FeS2 and assimilate Fe and S reduction products to meet nutrient demands. However, the mechanism of FeS2 mineral reduction and the forms of Fe and S assimilated by methanogens remained unclear. Thermodynamic calculations described herein indicate that H2 at aqueous concentrations as low as 10–10 M favors the reduction of FeS2, with sulfide (HS–) and pyrrhotite (Fe1–xS) as products; abiotic laboratory experiments confirmed the reduction of FeS2 with dissolved H2 concentrations greater than 1.98 × 10–4 M H2. Growth studies of Methanosarcina barkeri provided with FeS2 as the sole source of Fe and S resulted in H2 production but at concentrations too low to drive abiotic FeS2 reduction, based on abiotic laboratory experimental data. A strain of M. barkeri with deletions in all [NiFe]-hydrogenases maintained the ability to reduce FeS2 during growth, providing further evidence that extracellular electron transport (EET) to FeS2 does not involve H2 or [NiFe]-hydrogenases. Physical contact between cells and FeS2 was required for mineral reduction but was not required to obtain Fe and S from dissolution products. The addition of a synthetic electron shuttle, anthraquinone-2,6-disulfonate, allowed for biological reduction of FeS2 when physical contact between cells and FeS2 was prohibited, indicating that exogenous electron shuttles can mediate FeS2 reduction. Transcriptomics experiments revealed upregulation of several cytoplasmic oxidoreductases during growth of M. barkeri on FeS2, which may indicate involvement in provisioning low potential electrons for EET to FeS2. Collectively, the data presented herein indicate that reduction of insoluble FeS2 by M. barkeri occurred via electron transfer from the cell surface to the mineral surface resulting in the generation of soluble HS– and mineral-associated Fe1–xS. Solubilized Fe(II), but not HS–, from mineral-associated Fe1–xS reacts with aqueous HS– yielding aqueous iron sulfur clusters (FeSaq) that likely serve as the Fe and S source for methanogen growth and activity. FeSaq nucleation and subsequent precipitation on the surface of cells may result in accelerated EET to FeS2, resulting in positive feedback between cell activity and FeS2 reduction.

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Section: Resultsmentioning

confidence: 99%

Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction

et al. 2022

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“…The majority of the peaks remained in the same position. However, some of the peaks were intensified such as those at 2 θ =35.5° and 36.5° which corresponded to the pyrrhotite and pentlandite materials . Therefore, the potential cycling process was influencing the crystallinity of the material which subsequently resulted in a 3 fold improvement in the current density of the catalyst for the OER at 1.7 V (Figure S2).…”

Section: Resultsmentioning

confidence: 99%

Harnessing Native Iron Ore as an Efficient Electrocatalyst for Overall Water Splitting

2019

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Electrochemical water splitting is a widely accepted approach to generate hydrogen at a scale that is suitable for storing renewable energy. Therefore, the choice of catalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are critical in terms of cost when scaling up this technology. Thus, earth abundant transition metals oxides and sulfides have received significant attention as catalysts for the OER and HER, respectively. However, very few examples of actual Earth abundant materials mined from the Earth's crust have been used as electrocatalysts for these reactions. Here, we demonstrate that a raw iron ore is active for both the HER and OER under alkaline conditions, which is due to the natural abundance of the key elements of iron, nickel, and sulfur. The catalyst is stable for both reactions and can operate at 100 mA cm À 2 , which is comparable to many chemically synthesised nanomaterials based on these elements. This approach may be attractive for adding value to iron ore while minimising the cost of catalyst production.[a] Dr.

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“…Electrochemical systems have been recently suggested as a relevant approach to study prebiotic chemistry related to hydrothermal vents scenario (de Aldecoa et al, 2013 ; Barge et al, 2014 , 2015 ; Herschy et al, 2014 ; Yamaguchi et al, 2014 ; Roldan et al, 2015 ). The focus of these studies is usually on abiotic CO 2 reduction and reduced iron sulfides and sometimes iron oxides (green rust) are considered as possible electrode candidates.…”

Section: Discussionmentioning

confidence: 99%

Electron Transfer between Electrically Conductive Minerals and Quinones

Taran

2017

Front. Chem.

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Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite), and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and interactions between quinones and pyrite might have been an early analog of these ubiquitous systems.

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Natural Pyrrhotite as a Catalyst in Prebiotic Chemical Evolution

Cited by 9 publications

References 42 publications

Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction

Investigating Abiotic and Biotic Mechanisms of Pyrite Reduction

Harnessing Native Iron Ore as an Efficient Electrocatalyst for Overall Water Splitting

Electron Transfer between Electrically Conductive Minerals and Quinones

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