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department of
physics and astronomy
Microbe Power What can bacteria teach us about Energy,
the Environment, and Nanotechnology?
Moh El-Naggar
Physics and Astronomy, University of Southern California
Physics Instant Update: Workshop for High School Physics Teachers 06/24/2009
department of
physics and astronomy
A Los Angeles/SC High School Bioenergy Challenge?
•! Microbial Fuel Cells can be assembled with simple, inexpensive components. Can be built for high schools at USC.
•! Testing can be done with simple voltmeters
•! Proposing an annual workshop to train a teacher and ‘star’ student from each high school in building fuel cells.
•! Schools come back and compete a year later!
Interested? Contact me: [email protected]
department of
physics and astronomy
How it all started
Antony van Leeuwenhoek (1632-1723)
“For me, this was among all the marvels
that I discovered in nature the most
marvelous of all, and I must say, that for my
part, no more pleasant sight has met my eye
than this of so many thousand living
creatures in one small drop of water.”
http://www.ucmp.berkeley.edu/history/leeuwenhoek.html
department of
physics and astronomy
Bioenergy Environmental
Cleanup Uranium(VI)
Uranium(IV)
Nanotechnology
semiconductive nanotubes
magnetic nanoparticles
Lovley et al.1991. Nature 350:413-416.
Gorby et al. 1992 Environ. Sci.
Technol. 26:205-207.
Gorby et al, PNAS 103, 11358-11363 (2006)"
Ji-Hoon Lee et al. PNAS 104 20410-2041 (2007)
http://mfc-muri.usc.edu
Look what bacteria can do for us
department of
physics and astronomy
How they do it: Working with Electrons
Electron Donor "
(for food)"
Electron Acceptor "
(for breathing)"
•! e- flow along the cell membrane, through a series of carriers
•! H+ translocated across the membrane, charging a bio capacitor
•! Capacitor used to drive the synthesis of biologically useful energy i.e. ATP
department of
physics and astronomy
Shewanella oneidensis MR-1"Myers & Nealson, Science 240: 1319-1321, 1988"
e- donors!
Formate"
Lactate"
Pyruvate"
Amino Acids"
H2"
e- acceptors!
O2"
NO3-, NO2
-"
Mn(IV)"Mn(III)"Fe(III)"
Fumarate"DMSO"
S2O32-"
U(VI)"Cr(VI), Tc, As...."
S. oneidensis MR-1 growing on Fe2O3 (Pacific Northwest National Lab)"
•! Isolated in 1987
•! Very versatile: many donors & acceptors
•! Can “breathe solids”
How they do it: Metabolic Versatility
department of
physics and astronomy
Why this is remarkable: Extracellular Electron Transfer
•! Dissolved electron acceptors are accessible to intracellular machinery
•! But what about solids?
•! Opens up many possibilities: e.g. Bioenergy in Microbial Fuel Cells
Heidelberg et al, Nature Biotech. 20, 1118-1123, 2002"
MtrB 1776
MtrA 1777
MtrC 1778 OmcA 1779
…..
department of
physics and astronomy
How MFCs Work
•! Key feature here is ability to transfer electrons directly to anode"
•! Wide range of power densities reported: 16 - 4300 mW/m2"
•! Low power, but can live off any fuels in the natural environment!"
Anode (e.g. Shewanella w/ Lactate)"
Lactate- + 2H2O Acetate- + HCO3- + 5H+ + 4e-"
Cathode"
O2 + 4H+ + 4e- 2H2O"
department of
physics and astronomy
Microbial Fuel Cells
Bioengineered Fuel Cells: Optimization via Genetic Approaches and Multi-Scale Modeling"http://mfc-muri.usc.edu"
Nealson Lab (USC) Prakash Lab (USC)
department of
physics and astronomy
Bacterial Nanowires: A mechanism for direct
extracellular electron transport
Tapping mode AFM of S. oneidensis
MR-1 with bacterial nanowires and
membrane vesicles
Reductive transformation of hydrous
ferric oxide to Fe3O4 associated with
bacterial nanowires
Gorby et al, PNAS 103, 11358-11363 (2006)"Y.A. Gorby, J. McLean, A. Korenevsky, K. Rosso, M.Y. El-Naggar, and T.J. Beveridge. Geobiology 6, 232-241 (2008)
department of
physics and astronomy
Scanning Tunneling Microscopy
STM confirms the electrical conductivity of the bionanowires
How STM works Bacterial
Nanowire
Gorby et al, PNAS 103, 11358-11363 (2006)"
http://www.nisenet.org/ (Nanoscale Informal Science Education)
department of
physics and astronomy
What are they made of?
Deleting the genes responsible for certain proteins (electron transfer proteins)
results in non-conductive appendages
Gorby et al, PNAS 103, 11358-11363 (2006)"
department of
physics and astronomy
Interfacing Biology and Nanotechnology
Measuring individual bacterial nanowires from Shewanella
department of
physics and astronomy
Implications for microbial fuel cells
MFC anode before biofilm After biofilm formation and MFC
operation with Shewanella
Pacific Northwest National Lab
department of
physics and astronomy
What if it worked?
You think it’s easy running corporate R&D? It
was just fine, as long as the guy didn’t have
anything….The goddamn thing is just a germ
in a box! ……We can’t get into the face of our
fuel suppliers, telling them that we’re replacing
them with sugar water! We own our fuel
suppliers! It’d be like sawing off our own foot!
NATURE |Vol. 441| 18 May 2006
From Distraction, a science-fiction novel by
Bruce Sterling