Dissimilatory Reduction of Extracellular Electron Acceptors in Anaerobic Respiration

Abstract

An extension of the respiratory chain to the cell surface is necessary to reduce extracellular electron acceptors like ferric iron or manganese oxides. In the past few years, more and more compounds were revealed to be reduced at the surface of the outer membrane of Gram-negative bacteria, and the list does not seem to have an end so far. Shewanella as well as Geobacter strains are model organisms to discover the biochemistry that enables the dissimilatory reduction of extracellular electron acceptors. In both cases, c-type cytochromes are essential electron-transferring proteins. They make the journey of respiratory electrons from the cytoplasmic membrane through periplasm and over the outer membrane possible. Outer membrane cytochromes have the ability to catalyze the last step of the respiratory chains. Still, recent discoveries provided evidence that they are accompanied by further factors that allow or at least facilitate extracellular reduction. This review gives a condensed overview of our current knowledge of extracellular respiration, highlights recent discoveries, and discusses critically the influence of different strategies for terminal electron transfer reactions.

Microbial community structure and function of Nitrobenzene reduction biocathode in response to carbon source switchover

“…Cytochrome c proteins are essential for electrons transfer in dissimilatory anaerobic respiration of extracellular electrons acceptors and could also reverse the electrons transfer pathway for intracellular reductive metabolism (Lovley, 2012;Richter et al, 2012a;Ross et al, 2011). In this study, the detected outer membrane cytochrome c genes included decaheme OmcA/MtrC (Richter et al, 2012a), MtrF (a homologue of OmcA/MtrC) (Coursolle and Gralnick, 2010), and OmpA.…”

“…In this study, the detected outer membrane cytochrome c genes included decaheme OmcA/MtrC (Richter et al, 2012a), MtrF (a homologue of OmcA/MtrC) (Coursolle and Gralnick, 2010), and OmpA. Periplasmic multi-heme cytochrome c including one decaheme MtrA, 11 decaheme DmsE (a homologue of MtrA) (Coursolle and Gralnick, 2010), 3 inner membrane anchored (periplasm side) tetraheme NapC/NirT (a homologue of quinol dehydrogenase CymA) (McMillan et al, 2012) and 2 transmembrane high-molecular-weight cytochrome electron-transferring complexes were detected (Fig.…”

Deferrisoma palaeochoriense sp. nov., a thermophilic, iron(III)-reducing bacterium from a shallow-water hydrothermal vent in the Mediterranean Sea

“…Iron, the most abundant redox-active metal in today's Earth's crust, is thought to have served as one of the earliest electron acceptors for life's respiratory processes (Liu et al, 1997;Richter et al, 2012). This is, in part, supported by the widespread existence of bacteria and archaea capable of dissimilatory Fe(III) reduction in a variety of modern environments (Vargas et al, 1998;Slobodkin, 2005).…”

Towards patterned bioelectronics: facilitated immobilization of exoelectrogenic Escherichia coli with heterologous pili

“…More than 90 species have been reported to perform EET (Koch and Harnisch, 2017) including the EET model organisms Geobacter sulfurreducens and Shewanella oneidensis . Both species gain chemical energy in the form of ATP by coupling carbon oxidation to anaerobic reduction of metal oxide minerals such as Mn(III), Mn(IV), Fe(III), Cr(VI) and U(IV) in the extracellular space (Richter et al ., 2012). Despite the considerable number of reported electroactive microbes, the composition of their extracellular electron transfer pathway has remained largely unknown and is still limited to a small number of anode‐respiring bacteria (Kracke et al ., 2015).…”