Geobacterspecies have a number of important bioenergy applications. Recent studies have demonstrated that they can be abundant components of the microbial aggregates that form in anaerobic digestors converting organic wastes to methane. They can act as syntrophs, degrading organic compounds to acetate that methanogens in the aggregates then consume to produce methane. Electrons derived from Geobacter metabolism may be fed directly to the methanogens through electrically conductive networks that have been detected within the aggregates.
Some Geobacter species are capable of electrosynthesis, using electrons derived from electrodes to reduce carbon dioxide to fuels or other useful organic compounds.
One of the most studied bioenergy applications of Geobacter species is their ability to oxidize organic compounds with electron transfer to electrodes. Geobacter species were the first microorganisms found to derive energy to support growth from organic matter oxidation with an electrode serving as the sole electron acceptor and can produce the highest current densities of any pure culture. Geobacter species are often the microorganisms most highly enriched on electrodes harvesting electricity from a diversity of environments. Geobacter sulfurreducens has become the organism of choice for studying the mechanisms for direct electron transfer from microbial biofilms to electrodes. Recent studies have demonstrated that it produces highly conductive biofilms that promote electron transfer to the electrode and releases the c-type cytochrome, OmcZ, which accumulates at the biofilm-electrode interface to promote electron transfer to the electrode.
For publications on electrosynthesis please visit www.electrofuels.org
Derek R. Lovley and Kelly P. Nevin. 2011. A shift in the current: New applications and concepts for microbe-electrode electron exchange. Current Opinion in Biotechnology DOI 10.1016/j.copbio.2011.01.009
Kengo Inoue, Xinlei Qian, Leonor Morgado, Byoung-Chan Kim, Tünde Meste, Mounir Izallalen, Carlos A. Salgueiro, and Derek R. Lovley. 2010. Purification and characterization of OmcZ, an outer-surface, octaheme c-type cytochrome essential for optimal current production by Geobacter sulfurreducens. Appl Environ Microbiol 76(12):3999-4007.
Ashley E. Franks, Kelly P. Nevin, Richard H. Glaven, and Derek R. Lovley. 2010. Microtoming coupled to microarray analysis to evaluate the spatial metabolic status of Geobacter sulfurreducens biofilms. ISME J 4(4):509-519.
Kelly P. Nevin, Byoung-Chan Kim, Richard H. Glaven, Jessica P. Johnson, Trevor L. Woodard, Barbara A. Methé, Raymond J. DiDonato, Sean F. Covalla, Ashley E. Franks, Anna Liu, and Derek R. Lovley. 2009. Anode biofilm transcriptomics reveals outer surface components essential for high density current production in Geobacter sulfurreducens fuel cells. PLoS ONE 4(5):e5628.
Hanno Richter, Kelly P. Nevin, Hongfei Jia, Daniel A. Lowy, Derek R. Lovley and Leonard M. Tender. 2009. Cyclic voltammetry of biofilms of wild type and mutant Geobacter sulfurreducens on fuel cell anodes indicates possible roles of OmcB, OmcZ, type IV pili, and protons in extracellular electron transfer. Energy Environ Sci 2:506-516.
Hana Yi, Kelly P. Nevin, Byoung-Chan Kim, Ashley E. Franks, Anna Klimes, Leonard M. Tender, and Derek R. Lovley. 2009. Selection of a variant of Geobacter sulfurreducens with enhanced capacity for current production in microbial fuel cells. Biosens Bioelectron 24(12):3498-3503.
Ashley E. Franks, Kelly P. Nevin, Hongfei Jia, Mounir Izallalen, Trevor L. Woodard, and Derek R. Lovley. 2009. Novel strategy for three-dimensional real-time imaging of microbial fuel cell communities: monitoring the inhibitory effects of proton accumulation within the anode biofilm. Energy Environ Sci 2:113-119.
Derek R. Lovley 2008. The microbe electric: conversion of organic matter to electricity. Curr Opin Biotechnol 19(6):564-571.
Kelly P. Nevin, Hanno Richter, Sean F. Covalla, Jessica P. Johnson, Trevor L. Woodard, Amber L. Orloff, Hongfei Jia, M. Zhang, and Derek R. Lovley. 2008. Power output and columbic efficiencies from biofilms of Geobacter sulfurreducens comparable to mixed community microbial fuel cells. Environ Microbiol 10(10):2505-2514.
Hanno Richter, K. McCarthy, Kelly P. Nevin, Jessica P. Johnson, Vincent M. Rotello, and Derek R. Lovley. 2008. Electricity generation by Geobacter sulfurreducens attached to gold electrodes. Langmuir 24(8):4376-4379.
Martin Lanthier, Kelvin B. Gregory, and Derek R. Lovley. 2008. Growth with high planktonic biomass in Shewanella oneidensis fuel cells. FEMS Microbiol Lett 278(1):29-35.
Gemma Reguera, Kelly P. Nevin, Julie S. Nicoll, Sean F. Covalla, Trevor L. Woodard, and Derek R. Lovley. 2006. Appl Environ Microbiol 72(11):7345-7348.
Dawn E. Holmes, Swades K. Chaudhuri, Kelly P. Nevin, Teena Mehta, Barbara A. Methé, Anna Liu, Joy E. Ward, Trevor L. Woodard, Jennifer Webster, and Derek R. Lovley. 2006. Microarray and genetic analysis of electron transfer electrodes in Geobacter sulfurreducens. Environ Microbiol 8(10):1805-1815.
Derek R. Lovley 2006. Bug juice: Harvesting electricity with microorganisms. Nature Reviews Microbiology 4(7):497-508.
Derek R. Lovley 2006. Microbial fuel cells: Novel microbial physiologies and engineering approaches. Current Opinion in Biotechnology 17(3):327-332.
Daniel R. Bond, and Derek R. Lovley. 2005. Evidence for involvement of an electron shuttle in electricity generation by Geothrix fermentans. Appl Environ Microbiol 71(4):2186-2189.
Dawn E. Holmes, Daniel R. Bond, Regina A. O’Neil, Clare E. Reimers, Leonard R. Tender, and Derek R. Lovley. 2004. Microbial communities associated with electrodes harvesting electricity from a variety of aquatic sediments. Microb Ecol 48(2):178-190.
Dawn E. Holmes, Daniel R. Bond, and Derek R. Lovley. 2004. Electron transfer by Desulfobulbus propionicus to Fe(III) and graphite electrodes. Appl Environ Microbiol 70(2):1234-1237.
Daniel R. Bond, and Derek R. Lovley. 2003. Electricity production by Geobacter sulfurreducens attached to electrodes. Appl Environ Microbiol 69(3):1548-1555.
Leonard M. Tender, Clare E. Reimers, Hilmar A. Stecher, Dawn E. Holmes, Daniel R. Bond, Daniel A. Lowy, Kanoelani Pilobello, Stephanie J. Fertig, and Derek R. Lovley. 2002. Harnessing microbially generated power on the seafloor. Nat Biotechnol 20(8):821-825.
Daniel R. Bond, Dawn E. Holmes, Leonard M. Tender, and Derek R. Lovley. 2002. Electrode-reducing microorganisms that harvest energy from marine sediments. Science 295(5554):483-485.