Article

Selection of a variant of Geobacter sulfurreducens with enhanced capacity for current production in microbial fuel cells

Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Biosensors & Bioelectronics (Impact Factor: 6.45). 06/2009; 24(12):3498-503. DOI: 10.1016/j.bios.2009.05.004
Source: PubMed

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.

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    • "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. "
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    • "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 ). "
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