Methanol on the rocks: green rust transformation promotes the oxidation of methane

Orion Farr (1) , Nil Gaudu (2) , Gregoire Danger (3) , Michael Russell , Daniel Ferry (1) , Wolfgang Nitschke (2) , Simon Duval

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
2 BIP - Bioénergétique et Ingénierie des Protéines
3 PIIM - Physique des interactions ioniques et moléculaires

Shared coordination geometries between metal ions within reactive minerals and enzymatic metal cofactors hints at mechanistic and possibly evolutionary homology between particular abiotic chemical mineralogies and biological metabolism. The octahedral coordination of reactive Fe 2+/3+ minerals such as green rusts, endemic to anoxic sediments and the early Earth's oceans, mirrors the di-iron reaction centre of soluble methane monooxygenase (sMMO), responsible for methane oxidation in methanotrophy. We show that methane oxidation occurs in tandem with the oxidation of green rust to lepidocrocite and magnetite, mimicking radical-mediated methane oxidation found in sMMO to yield not only methanol but also halogenated hydrocarbons in the presence of seawater. This naturally occurring geochemical pathway for CH 4 oxidation elucidates a previously unidentified carbon cycling mechanism in modern and ancient environments and reveals clues into mineral-mediated reactions in the synthesis of organic compounds necessary for the emergence of life.

Domaines: Catalyse; Biochimie [q-bio.BM]

Orion Farr, Nil Gaudu, Gregoire Danger, Michael Russell, Daniel Ferry, et al.. Methanol on the rocks: green rust transformation promotes the oxidation of methane. Journal of the Royal Society Interface, 2023, 20 (206), pp.20230386. ⟨10.1098/rsif.2023.0386⟩. ⟨hal-04214469⟩