Leonard M. Tender Naval Research Laboratory Center for Bio/Molecular Science and Engineering, Washington, DC 20375 USA
From Mud to Electrode Catalysts and Conductive Nanomaterials
December 10, 2014
Shi L, et al. (2012) Molecular Underpinnings of Fe(III) Oxide Reduction by Shewanella oneidensis MR-1. Frontiers in microbiology 3.
Cat
ho
de
An
od
e
Bioelectrochemical Systems (BES) Microbial Electrochemistry/Electro-Microbiology
•Bacteria generate electrons
•Bacteria transfer electrons onto electrodes •Bio-anode can be a single species •Anaerobic
Microbial Bioanodes • Bacteria consume electrons. • Bacteria need carbon – CO2. • Cathode needs a consortium. • Bio-cathode consortia/synergy
Micobial Biocathodes
e-
e- e-
O2, CO2 C2HO
CO2
H2O, C2HO
Demonstrated bio-cathodes: • Bioremediation • Denitrification • Oxygen reduction • CO2 fixation
Demonstrated bio-anodes: •Organic matter oxidation (pure/sediments/wastes)
e- Biocathdode MCL
(seawater enriched)
Geobacter
Shewanella
mixed communities
FeRB
Mariprofundus ferrooxydans
mixed communities
FeOB
CBMSE 6.2 Review, June 18, 2003
1 - 10 cm
Depth-dependent sediment potential gradient - assay of marine sediment microbial activity
vs. SHE -0.2 V 0.6 V water
sediment
Limmol. Oceanogr. 1969, 14, 547-558
Pt microelectrode
w/insulating sheath
CBMSE 6.2 Review, June 18, 2003
Oxygen: (CH2O)106(NH3)16(HPO4) + 138O2 -181
106CO2 + 16HNO3 + H3PO4 + 122H2O
Manganese: (CH2O)106(NH3)16(HPO4) + 236MNO2 + 472H+ -175
236Mn2+ + 106CO2 + 8N2 + H3PO4 + 366H2O
Nitrate: (CH2O)106(NH3)16(HPO4) + 84.4HNO3 -156
106CO2 + 44.2N2 + H3PO4 + 148.4H2O + 16NH3
Iron: (CH2O)106(NH3)16(HPO4) + 424Fe2O3 + 484H+ -24
424Fe2+ + 106CO2 + 16NH3 + H3PO4 + 742H2O
Sulfate: (CH2O)106(NH3)16(HPO4) + 53SO42- -21
106CO2 + 16NH3 + H3PO4 + 53S2- + 106H2O
Methanogenesis: (CH2O)106(NH3)16(HPO4) -20
53CO2 + 53CH4 + 16NH3 + H3PO4
DGo (kJ/mole C6H12O6 )
Benthic Redox Gradient
1 -
10 c
m
Geocheim, Cosochim. Acta 1979, 43, 1075-1080
organic matter, oxidants
Anode
Cathode
XH H+ + X-
e-
e- e-
O2 + H+ H2O
H+
Anoxic
Sediment
Oxic
Water
O2 + C6H12O6 CO2 + H2O
aerobes
A fuel cell? Why?
Marine sediment &
seawater from a salt
marsh near
Tuckerton, New
Jersey USA,
39o 30.5’ N, 74o19.6’
W.
(5.5% Reduced
Carbon)
Marine sediment &
seawater from an
estuarine site within
Raritan Bay, New
Jersey,
40 o 27.5’ N,
74 o 04.4’ W
(3.2% Reduced Carbon)
Voltage and power density vs. current density for Identical
Pt Mesh-based fuel cells in different sediments, laboratory studies
0
1
2
3
4
De
pth
in
Se
dim
en
t (c
m)
0 2000 4000
Concentration (mM)
HS-
0
1
2
3
4
0 20 40
Concentration (mM)
HS-
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 2 4 6 8
Current Density (mA/m2)
Vo
ltag
e (
V)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Po
wer
Den
sit
y (
mW
att
/ m
2)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8
Current Density (mA/m2)
Vo
ltag
e (
V)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Po
wer
Den
sit
y (
mW
att
/ m
2)~1.2 mWatt/m2
~1.4 mWatt/m2
•low voltage
•ohmic
•mass transport limited
Reimers CE, Tender LM, Fertig S, Wang W. Harvesting energy from the marine sediment-water interface. Environmental Science & Technology 2001;35:192-5.
BMFC (Benthic Microbial Fuel Cell)
•full system integration: •regulate discharge of BUG at 0.35 V •convert 0.35 V to 6V •recharge capacitor to power RF TX for
real-time data •0.02W average draw (0.48 Wh/day, 175
Wh/yr, 10 alkaline D-cells/yr) •diver assisted deployment •ran flawlessly for 7 months until ice flow
severed mooring
J. Power Sources 2008, 179 (2), 571-575.
0
10
20
30
40
50
60
70
80
Tuckerton clone l ibrary results
current
no current
CFB Gram+ other
Per
cen
t of
clo
ne
lib
rary
• Enrichment in -subgroup from 23% to 75% • 45% of the enriched are Desulfuromonas acetoxidans: (oxidize acetate, reduce insoluble
iron/manganese oxides – FeRB)
• 24% are of the enriched are Desulfobulbus/Desulfocapsa: S0 →H2S + S04
-2
Science 295 (5554), 483-485 (2002). Nature Biotechnology 20 (8): 821-825 (2002).
Anode enrichment of iron-reducing microbes
16S ribosomal DNA (rDNA) genes
BMFC (Benthic Microbial Fuel Cell)
0
0.1
0.2
0.3
0.4
0.5
-50 0 50 100 150 200 250 300
Time (h)
Cells Acetate AQDS
65 °CC
urr
ent
(mA
)
Science 295 (5554), 483-485 (2002).
Columbic efficiency
85%
Columbic efficiency
99%
• pure culture D.
Acetoxidans
• when no mass transport limitations:10 A / m2
• Can grown biofilm by poising electrode at positive potential (0.5 V vs. SHE)
Bioelectrochemical Systems (BES) Microbial Electrochemisty/Electro-Microbiology
Anode
Cathode
C6H12O6 CH3CO2- H+ + CO2
Clostridium
e-
Geobacter
e- e-
O2 + H+ H2O
H+
Anoxic
Sediment
Oxic
Water
?
O2 + C6H12O6 CO2 + H2O
aerobes
BMFC (Benthic Microbial Fuel Cell)
C6H12O6
Nat. Biotechnol. 2002, 20 (8), 821-825.
external circuit
Ac
CO2, H+ e-
biofilm
anode
media
0 L z
e-
10 µm
anode e- ?
G. sulfurreducens
Bond DR, Strycharz-Glaven SM, Tender LM, & Torres CI (2012) On electron transport through Geobacter biofilms. ChemSusChem 5(6):1099-1105.
The Question:
Model of Extracellular Electron Transport
cell pili
Extracellular
Cytochrome
(EC)
Electron Hopping
Richter H, et al. (2009) Cyclic voltammetry of biofilms of wild type and mutant Geobacter sulfurreducens on fuel cell anodes indicates
possible roles of OmcB, OmcZ, type IV pili, and protons in extracellular electron transfer. Energy & Environmental Science 2:506-
516.
Strycharz SM, et al. (2011) Application of cyclic voltammetry to investigate enhanced catalytic current generation by biofilm-modified
anodes of Geobacter sulfurreducens strain DL1 vs. variant strain KN400. Energy Environ. Sci. 4(3):896-913.
Strycharz-Glaven SM & Tender LM (2012) Study of the mechanism of catalytic activity of G. sulfurreducens biofilm anodes during
biofilm growth. ChemSusChem 5(6):1106-1118.
cell pili
Extracellular
Cytochrome
(EC)
Mattick, J. S., Type IV pili and
twitching motility. In Annual Review
of Microbiology. Volume 56, 2002;
Vol. Volume 56, pp 289-314.
Feliciano, G. T.; da Silva, A. J. R.; Reguera, G.;
Artacho, E., Molecular and Electronic Structure of
the Peptide Subunit of Geobacter sulfurreducens
Conductive Phi from First Principles. J. Phys.
Chem. A 2012, 116 (30), 8023-8030.
Extracellular
Cytochrome
(EC)
Molecular structure of MtrF of S. oneidensis MR-1.
Molecular underpinnings of Fe(III) oxide reduction
by Shewanella oneidensis MR-1, Shi, L. et al.,
Front. Microbiol., 15 February 2012 | doi:
10.3389/fmicb.2012.0005
0 L z
anode biofilm
increasing portion of cytochromes
that are reduced
fraction of ECs in oxidized state
vs. distance form the electrode surface
Application of cyclic voltammetry to investigate enhanced catalytic current generation by biofilm-modified anodes of Geobacter sulfurreducens strain DL1 vs. variant strain KN400, Sarah M. Strycharz, Anthony P. Malanoski, Rachel M. Snider, Hana Yi, Derek R. Lovley and Leonard M. Tender, Energy Environ. Sci., 2011, 4, 896-913
1
•redox gradient
•diffusive EET
Fick’s 1st Law:
Dahms-Ruff:
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Ra
ma
n I
nte
nsity,
a.u
.
1420140013801360134013201300
Raman shift, cm-1
137113621315
14011412
Oxidation State Independent Peak Oxidation State Dependent Peaks
z = 0 mm
more oxidized z = 0 mm
more reduced
• ex situ
• ~1 mm spot diameter
• z = 0, 3, 6, 9 mm
mapping vibrational activity to the heme structure by using Density Functional Theory
Lebedev, N.; Strycharz-Glaven, S. M.; Tender, L. M., Spatially Resolved Confocal Resonant Raman Microscopic Analysis of Anode-
Grown Geobacter sulfurreducens Biofilms. ChemPhysChem 2014, 15 (2), 320-327.
Spectroscopic Slicing to Reveal Internal Redox Gradients in Electricity‐Producing Biofilms
Angewandte Chemie International Edition
Volume 52, Issue 3, pages 925-928, 26 NOV 2012 DOI: 10.1002/anie.201205440
http://onlinelibrary.wiley.com/doi/10.1002/anie.201205440/full#fig2
• in situ
Turnover during biofilm growth
Strycharz SM, et al. (2011) Application of cyclic voltammetry to investigate enhanced catalytic current generation by biofilm-modified
anodes of Geobacter sulfurreducens strain DL1 vs. variant strain KN400. Energy Environ. Sci. 4(3):896-913.
Diffusive Behavior
“EC mechanism”
Cyclic Voltammetry
Nernstian
Nicholson & Shain
45 mm
e- e- e- e-
Electrode 1 Electrode 2 Electrode 1 Electrode 2
media
biofilm
15 mm 15 mm
Snider RM, Strycharz-Glaven SM, Tsoi SD, Erickson JS, & Tender LM (2012) Long-range electron transport in Geobacter
sulfurreducens biofilms is redox gradient-driven. PNAS109(38):15467-15472.
InterDigitated microelectrode Array (IDA)
http://www.ijcambria.com/IDA_Electrode
_Cable_kit.pdf
biofilm
media
e- e- e- e- e-
Electrode 1 Drain
-0.475 V applied
Electrode 2 Source
-0.575 V applied
Electrode 1 Drain
-0.475 V applied
Electrode 2 Source
-0.575 V applied
IDA Gate Experiments
Cells only using UV filter EPS only using TRITC filter
Cells (stained with DAPI) are false colored red
EPS (stained with ConA-TRITC) are false colored green.
Electron Transport Across Fledgling Geobacter sulfurreducens Biofilms
Strycharz-Glaven SM, et al. (2014) Electron Transport through Early Exponential-Phase Anode-Grown Geobacter sulfurreducens
Biofilms. ChemElectroChem 1(11):1957-1965.
Strycharz-Glaven SM, et al. (2014) Electron Transport through Early Exponential-Phase Anode-Grown Geobacter sulfurreducens
Biofilms. ChemElectroChem 1(11):1957-1965.
Electron Transport Across Fledgling Geobacter sulfurreducens Biofilms