Selection of a variant of Geobacter sulfurreducens with enhanced capacity for current production in microbial fuel cells
ABSTRACT Geobacter sulfurreducens produces current densities in microbial fuel cells that are among the highest known for pure cultures. The possibility of adapting this organism to produce even higher current densities was evaluated. A system in which a graphite anode was poised at -400 mV (versus Ag/AgCl) was inoculated with the wild-type strain of G. sulfurreducens, strain DL-1. An isolate, designated strain KN400, was recovered from the biofilm after 5 months of growth on the electrode. KN400 was much more effective in current production than strain DL-1. This was apparent with anodes poised at -400 mV, as well as in systems run in true fuel cell mode. KN400 had current (7.6A/m(2)) and power (3.9 W/m(2)) densities that respectively were substantially higher than those of DL1 (1.4A/m(2) and 0.5 W/m(2)). On a per cell basis KN400 was more effective in current production than DL1, requiring thinner biofilms to make equivalent current. The enhanced capacity for current production in KN400 was associated with a greater abundance of electrically conductive microbial nanowires than DL1 and lower internal resistance (0.015 versus 0.130 Omega/m(2)) and mass transfer limitation in KN400 fuel cells. KN400 produced flagella, whereas DL1 does not. Surprisingly, KN400 had much less outer-surface c-type cytochromes than DL1. KN400 also had a greater propensity to form biofilms on glass or graphite than DL1, even when growing with the soluble electron acceptor, fumarate. These results demonstrate that it is possible to enhance the ability of microorganisms to electrochemically interact with electrodes with the appropriate selective pressure and that improved current production is associated with clear differences in the properties of the outer surface of the cell that may provide insights into the mechanisms for microbe-electrode interactions.
- SourceAvailable from: Pier-Luc Tremblay
[Show abstract] [Hide abstract]
- "Evidence suggest that Geobacter sulfurreducens can also reduce CO 2 into a multicarbon compound by MES (Soussan et al., 2013; Table 1). G. sulfurreducens is a well-characterized electrigenic bacterium generating power densities in oBESs as high as 3.9 W/m 2 (Yi et al., 2009). G. sulfurreducens pre-grown with acetate as an electron donor and carbon source was also shown to have the capacity to accept electrons from a cathode to reduce fumarate (Gregory et al., 2004; Dumas et al., 2008) or uranium(VI; Gregory and Lovley, 2005) after the depletion of acetate. "
ABSTRACT: Powering microbes with electrical energy to produce valuable chemicals such as biofuels has recently gained traction as a biosustainable strategy to reduce our dependence on oil. Microbial electrosynthesis (MES) is one of the bioelectrochemical approaches developed in the last decade that could have critical impact on the current methods of chemical synthesis. MES is a process in which electroautotrophic microbes use electrical current as electron source to reduce CO2 to multicarbon organics. Electricity necessary for MES can be harvested from renewable resources such as solar energy, wind turbine or wastewater treatment processes. The net outcome is that renewable energy is stored in the covalent bonds of organic compounds synthesized from greenhouse gas. This review will discuss the future of MES and the challenges that lie ahead for its development into a mature technology.Frontiers in Microbiology 03/2015; 6. DOI:10.3389/fmicb.2015.00201 · 3.94 Impact Factor
[Show abstract] [Hide abstract]
- "Pure cultures of bacteria such as Geobacter sulfurreducens have been shown to produce current densities as high as 7.1 A m −2 using an " H-cell " design with solid graphite electrodes though the biocatalytic capacity for power production in mixed consortia is generally about twice that of pure cultures of G. sulfurreducens (Ishii et al. 2008; Yi et al. 2009). Mixed species biofilms have been able to generate current densities of 12.7 and 26.2 "
ABSTRACT: Establishing a core microbiome is the first step in understanding and subsequently optimizing microbial interactions in anodic biofilms of microbial fuel cells (MFCs) for increased power, efficiency, and decreased start-up times. In the present study, we used 454 pyrosequencing to demonstrate that a core anodic community would consistently emerge over a period of 4 years given similar conditions. The development and variation across reactor designs of these communities was also explored. The core members present in all high-power generating biofilms were Geobacter, Aminiphilus, Sedimentibacter, Acetoanaerobium, and Spirochaeta, accounting for 72 ± 9 % of all genera. Aminiphilus spp., member of the Synergistetes phylum was present at higher abundances than previously reported in any other ecological studies. Results suggest a stable core microbiome in acetate-fed MFCs on both phylogenetic and functional levels.Applied Microbiology and Biotechnology 01/2014; 98(9). DOI:10.1007/s00253-013-5502-9 · 3.81 Impact Factor
[Show abstract] [Hide abstract]
- "There are several electrochemically active bacteria such as Shewanella putrifaciens , Geobacter sulfurreducens , Geobacter metallireducens , Enterobacter aerogenes , and Rhodoferax ferrireducens ( Kim et al. 2002 , Bond and Lovley 2003 , Chaudhuri and Lovley 2003 , Min et al. 2005a , Lovley 2006 , Schroder 2007 , Yi et al. 2009 , Zhou et al. 2011 ), which have the capability to transfer electrons from inside the cell to the extracellular acceptors through c-type cytochromes and microbial nanowires (flagella) present on their outer membrane. These form biofilms on the anode, which can further act as electron acceptors and transfer electrons to the anode from biocatalytic system, resulting in the production of more energy ( Chaudhuri and Lovley 2003 ). "
ABSTRACT: Microbial fuel cells (MFCs) are an emerging technology that has gained considerable attention in the recent years because they provide new opportunities for sustainable production of energy from a wide range of soluble complex organic wastes and renewable biomass. The driving force for research in this field has been the apprehension over the energy climate crisis and environment pollution. MFCs are bioreactors that can convert the chemical energy present in organic compounds into electrical energy. Presently, the literature shows that current and power yields are relatively low, but improvements in the technology can enhance these parameters as well as the efficiency of these cells. Sediment MFCs in powering low-powered electronic monitoring devices is one of the practical uses of MFCs. Additionally, MFCs can be used in implantable medical devices and wastewater treatment plants. This review discusses the factors governing the performance of these cells and the maximum power density that can be obtained using various combinations of substrates and microorganisms. Keywords: mediator; microbial fuel cell; microorganism; renewable energy;Reviews in Chemical Engineering 08/2013; 29(4):189–203. DOI:10.1515/revce-2013-0005 · 2.83 Impact Factor