Quantification of Electron Transfer Rates to a Solid
Phase Electron Acceptor through the Stages of Biofilm
Formation from Single Cells to Multicellular
Communities
Jeffrey S. McLean1*, Greg Wanger1, Yuri A. Gorby1, Martin Wainstein1, Jeff McQuaid1,
Shun’ ichi Ishii1, Orianna Bretschger1, Haluk Beyenal2, Kenneth H. Nealson1,3
1 The J. Craig Venter Institute, San Diego CA; 2 The Gene and Linda Voiland, School of
Chemical Engineering and Bioengineering and Center for Environmental, Sediment and
Aquatic Research, Washington State University, Pullman, WA; 3University of Southern
California, Los Angeles, CA
* Corresponding author Phone: 858-200-1843; Fax: (858) 200-1881; e-mail:
jmclean@jcvi.org
Supporting Information :
Figures ,S1, S2, S3, S4.
S1
Figure S1. Diagram of the optically compatible parallel plate flow chamber
retrofitted with fuel cell components. A) The flow chamber houses two polished
carbon anodes and an air cathode. B) Side profile view of the chamber showing
the positions of the components and the flow characteristics across the anode
surface.
Voltmeter
Voltmeter
Resistor
Resistor
Anodes
Non-conductive
Spacer
Inflow
Outflow
Ag\AgCl Reference
Cathode
Anodes
Cathode
Inflow
Outflow
Flow Path
Optical Window
A
B
S2
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
2
4
6
8
10
12
14
16
18
0
10 20 30 40 50 60 70 80
Current Density (µA/cm2)
Cell count (x 10
6
/cm
2
)
Time (h)
Cell Count 100 Ohm
Cell Count 1M Ohm
Current Density 1M Ohm
Current Density 100 Ohm
0
50
100
150
200
250
0
10 20 30 40 50 60 70 80
Current/cell ( fA/cell )
Time (h)
100 Ohm
1M Ohm
A
B
Figure S2. Replicate representative timecourse measurements of attached cell counts and
operating current over 72 hours on the 1M Ω and 100 Ω anode. A) Average cell counts per
cm2 of anode area (left axis) and the current density during operation (right axis). B)
Timecourse plot of the current generated per cell based on direct in-situ cell counts and the
stable operating current.
S3
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0
1
2
3
4
5
6
0
20
40
60
80
100
120
140