Exocellular electron transfer in anaerobic microbial communities

Alfons J.M. Stams*, Frank A.M. De Bok, Caroline M. Plugge, Miriam H.A. Van Eekert, Jan Dolfing, Gosse Schraa

*Corresponding author for this work

Research output: Contribution to journalShort surveypeer-review

299 Citations (Scopus)

Abstract

Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogenic bacteria and hydrogen-consuming methanogenic archaea. Anaerobic microorganisms that use insoluble electron acceptors for growth, such as iron- and manganese-oxide as well as inert graphite electrodes in microbial fuel cells, also transfer electrons exocellularly. Soluble compounds, like humic substances, quinones, phenazines and riboflavin, can function as exocellular electron mediators enhancing this type of anaerobic respiration. However, direct electron transfer by cell-cell contact is important as well. This review addresses the mechanisms of exocellular electron transfer in anaerobic microbial communities. There are fundamental differences but also similarities between electron transfer to another microorganism or to an insoluble electron acceptor. The physical separation of the electron donor and electron acceptor metabolism allows energy conservation in compounds as methane and hydrogen or as electricity. Furthermore, this separation is essential in the donation or acceptance of electrons in some environmental technological processes, e.g. soil remediation, wastewater purification and corrosion.

Original languageEnglish
Pages (from-to)371-382
Number of pages12
JournalEnvironmental Microbiology
Volume8
Issue number3
DOIs
Publication statusPublished - Mar 2006
Externally publishedYes

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