Goldschmidt 2012 Conference Abstracts
Competition Between Direct
Electron Transfer and Electron
Shuttling Pathways During
Microbial Fe(III) Respiration
MARTIAL TAILLEFERT1,*; JUSTIN BURNS2, SENG K. WEE2, AND
THOMAS J. DICHRISTINA2
1School
of Earth and Atmospheric Sciences, Georgia Institute of
Technology, Atlanta, USA, mtaillef@eas.gatech.edu (*
presenting author)
2School of Biology, Georgia Institute of Technology, Atlanta, USA,
thomas.dichristina@biology.gatech.edu
Several mechanisms have been proposed to explain how metalreducing bacteria transfer electrons to solid terminal electron
acceptors, yet the competition between the different pathways has not
been extensively investigated. In this study, the direct contact and the
electron-shuttling mechanisms involved in the anaerobic respiration
of different iron oxides by Shewanella oneidensis are compared to
determine whether these pathways are complementary or
competitive. Kinetic studies were conducted with the wild-type and a
mutant strain of S. oneidensis lacking an outer membrane porin
required for secretion of proteins postulated to be part of the terminal
reductase complex. A mathematical model was also developed that
accounts for the parallel reduction of iron oxides by the outer
membrane terminal reductase and the reduction of exogenous
electron-shuttling compounds. The model is calibrated using a suite
of independent experiments with the two different S. oneidensis
strains and the different iron oxides to investigate the competition
between these two pathways.
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