@article {3134,
	title = {Syntrophic growth with direct interspecies electron transfer as the primary mechanism for energy exchange.},
	journal = {Environ Microbiol Rep},
	volume = {5},
	year = {2013},
	month = {2013 Dec},
	pages = {904-10},
	abstract = {<p>Direct interspecies electron transfer (DIET) through biological electrical connections is an alternative to interspecies H2 transfer as a mechanism for electron exchange in syntrophic cultures. However, it has not previously been determined whether electrons received via DIET yield energy to support cell growth. In order to investigate this, co-cultures of Geobacter metallireducens, which can transfer electrons to wild-type G. sulfurreducens via DIET, were established with a citrate synthase-deficient G. sulfurreducens strain that can receive electrons for respiration through DIET only. In a medium with ethanol as the electron donor and fumarate as the electron acceptor, co-cultures with the citrate synthase-deficient G. sulfurreducens strain metabolized ethanol as fast as co-cultures with wild-type, but the acetate that G. metallireducens generated from ethanol oxidation accumulated. The lack of acetate metabolism resulted in less fumarate reduction and lower cell abundance of G. sulfurreducens. RNAseq analysis of transcript abundance was consistent with a lack of acetate metabolism in G. sulfurreducens and revealed gene expression levels for the uptake hydrogenase, formate dehydrogenase, the pilus-associated c-type cytochrome OmcS and pili consistent with electron transfer via DIET. These results suggest that electrons transferred via DIET can serve as the sole energy source to support anaerobic respiration.</p>},
	keywords = {Acetates, Anaerobiosis, Citrate (si)-Synthase, Cytochrome c Group, Electron Transport, Electrons, Energy Metabolism, Ethanol, Fimbriae, Bacterial, Formate Dehydrogenases, Fumarates, Geobacter, Oxidation-Reduction},
	issn = {1758-2229},
	doi = {10.1111/1758-2229.12093},
	author = {Shrestha, Pravin Malla and Rotaru, Amelia-Elena and Aklujkar, Muktak and Liu, Fanghua and Shrestha, Minita and Summers, Zarath M and Malvankar, Nikhil and Flores, Dan Carlo and Lovley, Derek R}
}
@article {404,
	title = {Interspecies electron transfer via hydrogen and formate rather than direct electrical connections in cocultures of Pelobacter carbinolicus and Geobacter sulfurreducens.},
	journal = {Appl Environ Microbiol},
	volume = {78},
	year = {2012},
	month = {2012 Nov},
	pages = {7645-51},
	abstract = {<p>Direct interspecies electron transfer (DIET) is an alternative to interspecies H(2)/formate transfer as a mechanism for microbial species to cooperatively exchange electrons during syntrophic metabolism. To understand what specific properties contribute to DIET, studies were conducted with Pelobacter carbinolicus, a close relative of Geobacter metallireducens, which is capable of DIET. P. carbinolicus grew in coculture with Geobacter sulfurreducens with ethanol as the electron donor and fumarate as the electron acceptor, conditions under which G. sulfurreducens formed direct electrical connections with G. metallireducens. In contrast to the cell aggregation associated with DIET, P. carbinolicus and G. sulfurreducens did not aggregate. Attempts to initiate cocultures with a genetically modified strain of G. sulfurreducens incapable of both H(2) and formate utilization were unsuccessful, whereas cocultures readily grew with mutant strains capable of formate but not H(2) uptake or vice versa. The hydrogenase mutant of G. sulfurreducens compensated, in cocultures, with significantly increased formate dehydrogenase gene expression. In contrast, the transcript abundance of a hydrogenase gene was comparable in cocultures with that for the formate dehydrogenase mutant of G. sulfurreducens or the wild type, suggesting that H(2) was the primary electron carrier in the wild-type cocultures. Cocultures were also initiated with strains of G. sulfurreducens that could not produce pili or OmcS, two essential components for DIET. The finding that P. carbinolicus exchanged electrons with G. sulfurreducens via interspecies transfer of H(2)/formate rather than DIET demonstrates that not all microorganisms that can grow syntrophically are capable of DIET and that closely related microorganisms may use significantly different strategies for interspecies electron exchange.</p>},
	keywords = {Coculture Techniques, Deltaproteobacteria, Electricity, Electron Transport, Electrons, Formates, Geobacter, Hydrogen, Microbial Interactions},
	issn = {1098-5336},
	doi = {10.1128/AEM.01946-12},
	author = {Rotaru, Amelia-Elena and Shrestha, Pravin M and Liu, Fanghua and Ueki, Toshiyuki and Nevin, Kelly and Summers, Zarath M and Lovley, Derek R}
}
@article {424,
	title = {Electrosynthesis of organic compounds from carbon dioxide is catalyzed by a diversity of acetogenic microorganisms.},
	journal = {Appl Environ Microbiol},
	volume = {77},
	year = {2011},
	month = {2011 May},
	pages = {2882-6},
	abstract = {Microbial electrosynthesis, a process in which microorganisms use electrons derived from electrodes to reduce carbon dioxide to multicarbon, extracellular organic compounds, is a potential strategy for capturing electrical energy in carbon-carbon bonds of readily stored and easily distributed products, such as transportation fuels. To date, only one organism, the acetogen Sporomusa ovata, has been shown to be capable of electrosynthesis. The purpose of this study was to determine if a wider range of microorganisms is capable of this process. Several other acetogenic bacteria, including two other Sporomusa species, Clostridium ljungdahlii, Clostridium aceticum, and Moorella thermoacetica, consumed current with the production of organic acids. In general acetate was the primary product, but 2-oxobutyrate and formate also were formed, with 2-oxobutyrate being the predominant identified product of electrosynthesis by C. aceticum. S. sphaeroides, C. ljungdahlii, and M. thermoacetica had high (>80\%) efficiencies of electrons consumed and recovered in identified products. The acetogen Acetobacterium woodii was unable to consume current. These results expand the known range of microorganisms capable of electrosynthesis, providing multiple options for the further optimization of this process.},
	keywords = {Acetobacterium, Carbon Dioxide, Clostridium, Electrodes, Electrons, Moorella, Organic Chemicals, Oxidation-Reduction, Veillonellaceae},
	issn = {1098-5336},
	doi = {10.1128/AEM.02642-10},
	author = {Nevin, Kelly P and Hensley, Sarah A and Franks, Ashley E and Summers, Zarath M and Ou, Jianhong and Woodard, Trevor L and Snoeyenbos-West, Oona L and Lovley, Derek R}
}
@article {431,
	title = {Direct exchange of electrons within aggregates of an evolved syntrophic coculture of anaerobic bacteria.},
	journal = {Science},
	volume = {330},
	year = {2010},
	month = {2010 Dec 3},
	pages = {1413-5},
	abstract = {Microbial consortia that cooperatively exchange electrons play a key role in the anaerobic processing of organic matter. Interspecies hydrogen transfer is a well-documented strategy for electron exchange in dispersed laboratory cultures, but cooperative partners in natural environments often form multispecies aggregates. We found that laboratory evolution of a coculture of Geobacter metallireducens and Geobacter sulfurreducens metabolizing ethanol favored the formation of aggregates that were electrically conductive. Sequencing aggregate DNA revealed selection for a mutation that enhances the production of a c-type cytochrome involved in extracellular electron transfer and accelerates the formation of aggregates. Aggregate formation was also much faster in mutants that were deficient in interspecies hydrogen transfer, further suggesting direct interspecies electron transfer.},
	keywords = {Anaerobiosis, Bacterial Proteins, Biological Evolution, Culture Media, Cytochrome c Group, Electron Transport, Electrons, Ethanol, Fimbriae Proteins, Geobacter, Hydrogen, Microbial Consortia, Microbial Interactions, Mutation, Oxidation-Reduction, Selection, Genetic},
	issn = {1095-9203},
	doi = {10.1126/science.1196526},
	author = {Summers, Zarath M and Fogarty, Heather E and Leang, Ching and Franks, Ashley E and Malvankar, Nikhil S and Lovley, Derek R}
}
