A Caltech Library Service

Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments

Kopf, Sebastian H. and Henny, Cynthia and Newman, Dianne K. (2013) Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments. Environmental Science and Technology, 47 (6). pp. 2602-2611. ISSN 0013-936X. PMCID PMC3604861.

PDF (ACS AuthorChoice) - Published Version
See Usage Policy.

PDF - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


This study introduces a newly isolated, genetically tractable bacterium (Pseudogulbenkiania sp. strain MAI-1) and explores the extent to which its nitrate-dependent iron-oxidation activity is directly biologically catalyzed. Specifically, we focused on the role of iron chelating ligands in promoting chemical oxidation of Fe(II) by nitrite under anoxic conditions. Strong organic ligands such as nitrilotriacetate and citrate can substantially enhance chemical oxidation of Fe(II) by nitrite at circumneutral pH. We show that strain MAI-1 exhibits unambiguous biological Fe(II) oxidation despite a significant contribution (~30–35%) from ligand-enhanced chemical oxidation. Our work with the model denitrifying strain Paracoccus denitrificans further shows that ligand-enhanced chemical oxidation of Fe(II) by microbially produced nitrite can be an important general side effect of biological denitrification. Our assessment of reaction rates derived from literature reports of anaerobic Fe(II) oxidation, both chemical and biological, highlights the potential competition and likely co-occurrence of chemical Fe(II) oxidation (mediated by microbial production of nitrite) and truly biological Fe(II) oxidation.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Kopf, Sebastian H.0000-0002-2044-0201
Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2013 American Chemical Society. ACS AuthorChoice. Received: March 22, 2012. Revised: February 6, 2013. Accepted: February 12, 2013. Published: February 12, 2013. We thank Jim Morgan for many insightful conversations and inspiring S.H.K. to pursue this project, Sean Crowe, CarriAyne Jones, Arne Sturm, Sulung Nomosatryo, David Fowle, and Don Canfield for sample acquisition and fieldwork in Indonesia, Nathan Dalleska and the Caltech Environmental Analysis Center for instrumentation that benefited this project, Andreas Kappler, Nicole Klüglein, and Jay Labinger for helpful discussions, members of the Newman Lab and the anonymous reviewers for constructive criticism that improved the manuscript. This work was supported by grants to D.K.N from the Dreyfus Foundation and the Howard Hughes Medical Institute (HHMI). D.K.N. is an HHMI Investigator. S.H.K. is an HHMI International Student Research Fellow. The authors declare no competing financial interest.
Funding AgencyGrant Number
Camille and Henry Dreyfus FoundationUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Issue or Number:6
PubMed Central ID:PMC3604861
Record Number:CaltechAUTHORS:20130429-093249361
Persistent URL:
Official Citation: Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments Sebastian H. Kopf, Cynthia Henny, and Dianne K. Newman Environmental Science & Technology 2013 47 (6), 2602-2611
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38149
Deposited By: Ruth Sustaita
Deposited On:29 Apr 2013 16:56
Last Modified:15 Jun 2020 17:41

Repository Staff Only: item control page