Evaluation of electron-shuttling compounds in microbial ferric iron reduction.

Electron shuttling via humic acids in microbial iron(III) reduction in a freshwater sediment.

The biological and chemical potential for electron shuttling via humic acids was evaluated by analyzing the depth distribution of humic-acid-reducing and iron-reducing bacteria in a freshwater sediment, and correlating it to the redox characteristics of humic acids and iron. Physicochemical analysis of profundal sediments of Lake Constance revealed a distinct stratification, with oxygen respira...

Lack of production of electron-shuttling compounds or solubilization of Fe(III) during reduction of insoluble Fe(III) oxide by Geobacter metallireducens.

Studies with the dissimilatory Fe(III)-reducing microorganism Geobacter metallireducens demonstrated that the common technique of separating Fe(III)-reducing microorganisms and Fe(III) oxides with semipermeable membranes in order to determine whether the Fe(III) reducers release electron-shuttling compounds and/or Fe(III) chelators is invalid. This raised doubts about the mechanisms for Fe(III)...

Lack of Production of Electron-Shuttling Compounds or Solubilization of Fe(III) During Reduction of Insoluble Fe(III) Oxide of Geobacter Metallireducens

Biochar-Facilitated Microbial Reduction of Hematite.

As an important component of soil organic matter (SOM), the transformation of pyrogenic carbon plays a critical role in the biogeochemical cycles of carbon and other redox-active elements such as iron (Fe). Herein, we studied the influences of wheat straw-derived biochars on the microbial reduction of 100 mM of hematite by the dissimilatory metal reducing bacteria Shewanella oneidensis MR-1 und...

Anaerobic Sediments

The potential for ferric iron reduction with fermentable substrates, fermentation products, and complex organic matter as electron donors was investigated with sediments from freshwater and brackish water sites in the Potomac River Estuary. In enrichments with glucose and hematite, iron reduction was a minor pathway for electron flow, and fermentation products accumulated. The substitution of a...