Evaluation of electron-shuttling compounds in microbial ferric iron reduction.
Iron-reducing bacteria can transfer electrons to ferric iron oxides which are barely soluble at neutral pH, and electron-shuttling compounds or chelators are discussed to be involved in this process. Experiments using semipermeable membranes for separation of ferric iron-reducing bacteria from ferric iron oxides do not provide conclusive results in this respect. Here, we used ferrihydrite embedded in 1% agar to check for electron-shuttling compounds in pure and in enrichment cultures. Geobacter sulfurreducens reduced spatially distant ferrihydrite only in the presence of anthraquinone-2,6-disulfonate, a small molecule known to shuttle electrons between the bacterial cell and ferrihydrite. However, indications for the production and excretion of electron-shuttling compounds or chelators were found in ferrihydrite-containing agar dilution cultures that were inoculated with ferric iron-reducing enrichment cultures.
Straub
Kristina L
KL
Fakultät für Biologie, Universität Konstanz, 78457 Konstanz, Germany. kristina.straub@uni-konstanz.de
Schink
Bernhard
B
D000880:Anthraquinones / Q000378:metabolism; D003574:Cytochrome c Group / Q000737:chemistry; D020564:Deltaproteobacteria / Q000254:growth & development / Q000378:metabolism*; D004579:Electron Transport; D005290:Ferric Compounds / Q000378:metabolism*; D005293:Ferritins / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction
D000880:Anthraquinones; D003574:Cytochrome c Group; D005290:Ferric Compounds; C408124:anthraquinone-2,6-disulfonate; C000499:ferric oxide; C092844:ferric oxyhydroxide; D005293:Ferritins; D007501:Iron