Redox potential dependent respiration by Geobacter sulfurreducens

Abstract

Geobacter sulfurreducens is a Gram negative δ-proteobacteria with the ability to couple the internal oxidation of a carbon and electron donor with the external reduction of extracellular electron acceptors. Extracellular electron acceptors utilized by G. sulfurreducens include insoluble Fe(III)- and Mn(IV)-oxides, electrodes poised at accepting potentials, and a variety of soluble acceptors including humic acids and chelated metals. These substrates exist over a redox potential window greater than 0.5 V, suggesting that respiratory flexibility to efficiently take advantage of electron acceptors with different redox potentials would be a useful trait. The data presented within this thesis demonstrate that G. sulfurreducens uses multiple electron transfer pathways for the reduction of extracellular electron acceptors of different redox potentials.