%0 Journal Article
%A Michelson, Kyle
%A Sanford, Robert A.
%A Valocchi, Albert J.
%A Werth, Charles J.
%D 2017
%T Nanowires
of Geobacter sulfurreducens Require Redox Cofactors
to Reduce Metals in Pore Spaces Too Small
for Cell Passage
%U https://acs.figshare.com/articles/journal_contribution/Nanowires_of_i_Geobacter_sulfurreducens_i_Require_Redox_Cofactors_to_Reduce_Metals_in_Pore_Spaces_Too_Small_for_Cell_Passage/5462149
%R 10.1021/acs.est.7b02531.s001
%2 https://ndownloader.figshare.com/files/9445906
%K results discount electron
%K Geobacter nanowires
%K 15 μ m
%K sediment
%K pore
%K 40 μ m
%K 1.4 μ m
%K Cell Passage Members
%K Mn
%K Geobacter sulfurreducens
%K length
%K Fe
%K oxide
%K birnessite
%K extracellular electron transport
%K AQDS
%X Members of the Geobacteraceae family
are ubiquitous metal reducers
that utilize conductive “nanowires” to reduce Mn(IV)
and Fe(III) oxides in anaerobic sediments. However, it is not currently
known if and to what extent the Mn(IV) and Fe(III) oxides in soil
grains and low permeability sediments that are sequestered in pore
spaces too small for cell passage can be reduced by long-range extracellular
electron transport via Geobacter nanowires, and what
mechanisms control this reduction. We developed a microfluidic reactor
that physically separates Geobacter sulfurreducens from the Mn(IV) mineral birnessite by a 1.4 μm thick wall
containing <200 nm pores. Using optical microscopy and Raman spectroscopy,
we show that birnessite can be reduced up to 15 μm away from
cell bodies, similar to the reported length of Geobacter nanowires. Reduction across the nanoporous wall required reducing
conditions, provided by Escherichia coli, and an
exogenous supply of riboflavin. Our results discount electron shuttling
by dissolved flavins, and instead support their role as bound redox
cofactors in electron transport from nanowires to metal oxides. We
also show that upon addition of a soluble electron shuttle (i.e.,
AQDS), reduction extends beyond the reported nanowire length up to
40 μm into a layer of birnessite.
%I ACS Publications