A severe reduction in the cytochrome C content of Geobacter sulfurreducens eliminates its capacity for extracellular electron transfer. Issue 2 (17th December 2014)

• Record Type: Journal Article
• Authors: Estevez‐Canales, Marta; Kuzume, Akiyoshi; Borjas, Zulema; Füeg, Michael; Lovley, Derek; Wandlowski, Thomas; Esteve‐Núñez, Abraham
• Is Part Of: Environmental microbiology reports. Volume 7:Issue 2(2015)
• Page Start: 219
• Page End: 226
• Publication Date: 2014-12-17
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12230
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The ability of <italic>G</italic><italic>eobacter</italic> species to transfer electrons outside the cell enables them to play an important role in a number of biogeochemical and bioenergy processes. Gene deletion studies have implicated periplasmic and outer‐surface <italic>c</italic>‐type cytochromes in this extracellular electron transfer. However, even when as many as five <italic>c</italic>‐type cytochrome genes have been deleted, some capacity for extracellular electron transfer remains. In order to evaluate the role of <italic>c</italic>‐type cytochromes in extracellular electron transfer, <italic>G</italic><italic>eobacter sulfurreducens</italic> was grown in a low‐iron medium that included the iron chelator (<italic>2</italic>, <italic>2</italic>′‐<italic>bipyridine)</italic> to further sequester iron. Haem‐staining revealed that the cytochrome content of cells grown in this manner was 15‐fold lower than in cells exposed to a standard iron‐containing medium. The low cytochrome abundance was confirmed by in situ nanoparticle‐enhanced Raman spectroscopy (NERS). The cytochrome‐depleted cells reduced fumarate to succinate as well as the cytochrome‐replete cells do, but were unable to reduce Fe(III) citrate or to exchange electrons with a graphite electrode. These results demonstrate that <italic>c</italic>‐type cytochromes are essential for extracellular electron transfer by <italic>G</italic><italic>. sulfurreducens</italic>. The strategy for growing cytochrome‐depleted <italic>G</italic><italic>. sulfurreducens</italic> will also greatly aid future physiological studies of <italic>Geobacter</italic> species and other microorganisms capable of extracellular electron transfer.</p> </abstract>