Interspecies exchange of electrons enables a diversity of microbial communities to gain energy from reactions that no one microbe can catalyze. The first recognized strategies for interspecies electron transfer were those that relied on chemical intermediates that are recycled through oxidized and reduced forms. Well-studied examples are interspecies H2 transfer and the cycling of sulfur intermediates in anaerobic photosynthetic communities. Direct interspecies electron transfer (DIET) in which two species establish electrical contact is an alternative. Electrical contacts documented to date include electrically conductive pili, as well as conductive iron minerals and conductive carbon moieties such as activated carbon and biochar. Interspecies electron transfer is central to the functioning of methane-producing microbial communities. The importance of interspecies H2 transfer in many methanogenic communities is clear, but under some circumstances DIET predominates. It is expected that further mechanistic studies and broadening investigations to a wider range of environments will help elucidate the factors that favor specific forms of interspecies electron exchange under different environmental conditions.
Keywords: syntrophy, diet, interspecies electron transfer, conductive pili, coculture
Citation: Shrestha PM and Rotaru A-E (2014) Plugging in or going wireless: strategies for interspecies electron transfer. Front. Microbiol. 5:237. doi: 10.3389/fmicb.2014.00237
Received: 28 March 2014; Accepted: 30 April 2014;
Published online: 16 May 2014.
Edited by:Luis Raul Comolli, Lawrence Berkeley National Laboratory, USA
Reviewed by:Wei Shi, North Carolina State University, USA
Copyright © 2014 Shrestha and Rotaru. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Pravin Malla Shrestha, Energy Biosciences Institute, University of California, Berkeley, CA 94704, USA e-mail: firstname.lastname@example.org