Investigation of Marine
Sediment Microbial Populations in Microbial Fuel Cells
Many bacteria can convert chemical energy to
electrical energy: they oxidize diverse organic substrates,
electrons to anodic electrodes and thus generate electricity
microbial fuel cells (MFCs). In the marine environment, microbial
fuel cells termed either sediment or benthic microbial fuel
have been developed to generate power via anodic bacteria in
ocean sediment. Power is dependent upon enriched anodic
bacteria that transport their electrons onto the anode. The
marine-deployed MFC systems can provide renewable, harvested
power to trickle charge batteries or other storage devices.
Through power management systems these storage devices can
power traditional electronic loads of interest. The systems
promise to allow for long term deployment of in-water sensor
communications systems, providing decreased maintenance and
increased operational capabilities.
At SSC Pacific,
MFC prototypes have been tested
and evaluated in a field environment to determine their
potential to power devices such as acoustic arrays. Two prototype
MFC systems specifically developed to facilitate examination
of the temporal and spatial response of anodic bacteria in
marine MFCs were deployed in
the San Diego Bay over a 60-day time period.
Both had identical cathodes, load electronics,
and data acquisition devices. The two systems had different
anode architecture; one was called the 'Eel' and
the other the 'Octopus' (see
of bacteria on, and/or adjacent to the graphite sheet anodes
allowed for the determination of the most probable number (MPN)
of iron-reducing bacteria over time. For the 'Eel',
sediment cores were taken near, between, and 15 cm away from
the anodes. The 'Octopus' MFC was constructed
to allow sacrificial removal of anode material for direct swabbing
of the anode.
Figure 1. Schematic of the ‘Eel’ and
'Octopus' MFC system designed to take bacterial samples.
A. 'Eel' design,
10x30 cm sheet graphite electrodes on redwood
backplane (not shown, see Figure 2) attached to electronic
cabling. B. 'Octopus' design, 5x5 cm attached to electronic
cabling. In both, the sealed electronics package
lies directly on the ocean sediment. The graphite filament
electrode is suspended in the marine water column to
Figure 2. Microbial fuel cells
designed specifically for bacterial sampling over time.
'Eel' MFC top
(A) and bottom (B) viewpoints with backplane installed;
C is the 'Octopus' MFC. A. Top view of the redwood
board with holes drilled to enable sediment core sampling
to occur adjacent to (outside holes), and ~2 cm away
from the two anodes (center hole). B. Bottom view to
visualize the two anodes placed 5.5 cm apart; placed
for sampling in the space between the two anodes. C.
'Octopus' MFC; nine small 7x7 cm sacrificial anodes
attached to an underwater deployable electronics package.
- Molecular Biology/Microbiology Laboratory
- Pier facilities
- Diver support services
- Ocean engineering expertise
- Arias-Thode, Y.M., K. Richter,
A. Wotawa-Bergen, D.B. Chadwick, J. Kan,
and K. Nealson. 2011. Development of Microbial Fuel Cell
Prototypes for Examination of the Temporal and Spatial Response
of Anodic Bacterial Communities in Marine Sediments. IEEE
OCEANS 2011, Santander, Spain, June 6-9, 2011.