Open AccessThermodynamic controls on rates of iron oxide reduction by extracellular electron shuttles
Author(s) -
Meret Aeppli,
Sébastien Giroud,
Sanja Vranic,
Andreas Voegelin,
Thomas B. Hofstetter,
Michael Sander
Publication year - 2022
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2115629119
Subject(s) - exergonic reaction , electron transfer , chemistry , electron acceptor , redox , oxide , anoxic waters , ferric , ferrous , iron oxide , inorganic chemistry , hydrous ferric oxides , anaerobic respiration , anaerobic exercise , photochemistry , environmental chemistry , catalysis , biochemistry , organic chemistry , biology , physiology , sorption , adsorption
Significance Under anoxic conditions, various microorganisms couple the oxidation of organic carbon to the reduction of solid ferric iron oxide phases using extracellular electron shuttles (EES). Determining the contribution of this widespread terminal electron accepting process to total anaerobic respiration has proven challenging because of large variations in observed ferric iron reduction rates. This study demonstrates that rates of ferric iron oxide reduction by EES can be rationalized based on a unifying relationship that links rates to the thermodynamic driving force for the least favorable electron transfer from the EES to ferric iron. The relationship derived herein allows for a generalized and precise assessment of the contribution of EES-facilitated ferric iron oxide reduction to organic matter decomposition in anoxic environments.