Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments
نویسندگان
چکیده
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.
منابع مشابه
Iron Sulfide-arsenite Interactions: Adsorption Behavior onto Iron Monosulfides and Controls on Arsenic Accumulation in Pyrite
Arsenic mobility in natural systems is often linked to iron and sulfur cycling at redox boundaries, apparently due to co-precipitation reactions of arsenic with poorly crystalline iron (oxy)hydroxides, iron monosulfides, and pyrite (e.g., Edenborn et al., 1986; Moore et al., 1988). The mobility of arsenic under anoxic, sulfate-reducing conditions is expected to be governed by interactions betwe...
متن کاملSuboxic deposition of ferric iron by bacteria in opposing gradients of Fe(II) and oxygen at circumneutral pH.
The influence of lithotrophic Fe(II)-oxidizing bacteria on patterns of ferric oxide deposition in opposing gradients of Fe(II) and O(2) was examined at submillimeter resolution by use of an O(2) microelectrode and diffusion microprobes for iron. In cultures inoculated with lithotrophic Fe(II)-oxidizing bacteria, the majority of Fe(III) deposition occurred below the depth of O(2) penetration. In...
متن کاملAssessment of effective factors on bacterial oxidation of ferrous iron by focusing on sweetening natural gas
In this study, the effects of some factors on bacterial growth and ferrous oxidation rates were investigated by Acidithiobacillus ferrooxidan in 250 ml shake flasks. One factor at a time (OFAT) design approach was used for preliminary evaluation of various factors affecting the process, such as pH, initial ferrous and elemental sulfur concentrations, shaker agitation rate, and liquid to flask v...
متن کاملFe(III) Oxide Reactivity Toward Biological versus Chemical Reduction
Initial rates of biological (Shewanella putrefaciens strain CN32, pH 6.8) and chemical (ascorbate, pH 3.0) reduction of synthetic Fe(III) oxides with a broad range of crystallinity and specific surface area were examined to assess how variations in these properties are likely to influence the kinetics of bacterial Fe(III) oxide reduction in heterogeneous natural Fe(III) oxide assemblages. The r...
متن کاملImmobilization of Acidithiobacillus Ferrooxidans on Monolithic Packing for Biooxidation of Ferrous Iron
The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the...
متن کامل