TY - JOUR
T1 - A kinetic perspective on extracellular electron transfer by anode-respiring bacteria
AU - Torres, Cesar
AU - Marcus, Andrew
AU - Lee, Hyung Sool
AU - Parameswaran, Prathap
AU - Krajmalnik-Brown, Rosa
AU - Rittmann, Bruce
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010/1
Y1 - 2010/1
N2 - In microbial fuel cells and electrolysis cells (MXCs), anode-respiring bacteria (ARB) oxidize organic substrates to produce electrical current. In order to develop an electrical current, ARB must transfer electrons to a solid anode through extracellular electron transfer (EET). ARB use various EET mechanisms to transfer electrons to the anode, including direct contact through outer-membrane proteins, diffusion of soluble electron shuttles, and electron transport through solid components of the extracellular biofilm matrix. In this review, we perform a novel kinetic analysis of each EET mechanism by analyzing the results available in the literature. Our goal is to evaluate how well each EET mechanism can produce a high current density (>10 A m-2) without a large anode potential loss (less than a few hundred millivolts), which are feasibility goals of MXCs. Direct contact of ARB to the anode cannot achieve high current densities due to the limited number of cells that can come in direct contact with the anode. Slow diffusive flux of electron shuttles at commonly observed concentrations limits current generation and results in high potential losses, as has been observed experimentally. Only electron transport through a solid conductive matrix can explain observations of high current densities and low anode potential losses. Thus, a study of the biological components that create a solid conductive matrix is of critical importance for understanding the function of ARB.
AB - In microbial fuel cells and electrolysis cells (MXCs), anode-respiring bacteria (ARB) oxidize organic substrates to produce electrical current. In order to develop an electrical current, ARB must transfer electrons to a solid anode through extracellular electron transfer (EET). ARB use various EET mechanisms to transfer electrons to the anode, including direct contact through outer-membrane proteins, diffusion of soluble electron shuttles, and electron transport through solid components of the extracellular biofilm matrix. In this review, we perform a novel kinetic analysis of each EET mechanism by analyzing the results available in the literature. Our goal is to evaluate how well each EET mechanism can produce a high current density (>10 A m-2) without a large anode potential loss (less than a few hundred millivolts), which are feasibility goals of MXCs. Direct contact of ARB to the anode cannot achieve high current densities due to the limited number of cells that can come in direct contact with the anode. Slow diffusive flux of electron shuttles at commonly observed concentrations limits current generation and results in high potential losses, as has been observed experimentally. Only electron transport through a solid conductive matrix can explain observations of high current densities and low anode potential losses. Thus, a study of the biological components that create a solid conductive matrix is of critical importance for understanding the function of ARB.
KW - Electron shuttles
KW - Microbial electrolysis cells
KW - Microbial fuel cells
KW - Microbial nanowires
KW - Nernst-Monod kinetics
KW - Solid conductive matrix
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U2 - 10.1111/j.1574-6976.2009.00191.x
DO - 10.1111/j.1574-6976.2009.00191.x
M3 - Review article
C2 - 19895647
AN - SCOPUS:71549170875
SN - 0168-6445
VL - 34
SP - 3
EP - 17
JO - FEMS Microbiology Reviews
JF - FEMS Microbiology Reviews
IS - 1
ER -