harnessing microbe-electrode interactions for bioenergy
TRANSCRIPT
Harnessing microbe-electrode
interactions for bioenergy
MSU BioEconomy Institute, March 16th, 2016
Dr. Michaela A. TerAvest
Assistant Professor, Biochemistry and Molecular Biology
Thanks to:
Lars Angenent
(Cornell)
LBNL/UC Berkeley Team
MSU
Biomanufacturing abates
global problems
3
environmental
degradation
pollution climate change
Genetically engineered microbes
are essential to biomanufacturing
4Choi, Yong Jun, and Sang
Yup Lee. Nature (2013).
Overhage, Steinbüchel,
and Priefert. AEM (2003).
Farmer and Liao.
Nat Biotech (2000).
fuels chemicals pharmaceuticals
Reliance on native pathways
hinders biomanufacturing
5Martinez et al.
Metab. Eng. (2008).
Further modification can address
specific inefficiencies
6
My approach combines
electrochemistry and synbio
7
Utilizing electrodes to control
metabolic electron flow
8TerAvest and Angenent.
ChemElectroChem (2014).
Shewanella oneidensis MR-1
9
• Isolated from Lake Oneida, NY sediments
• Respires with:– oxygen
– nitrate
– iron
– manganese
– chromium
– uranium
– electrodes
Photo by Dr. Miriam Rosenbaum
Cytochromes connect
electrodes to metabolism
10
Electrode controls
metabolic rate and efficiency
11TerAvest and Angenent.
ChemElectroChem (2014).
Electrochemistry is a powerful tool
for metabolic control
12
Understanding energy partitioning
by the electron transport chain
13
ATP DNA replication
PMF transport and motility
NAD(P)H biosynthesis
Electron transport mutant
produces more current than WT
14
How does Δnuo
influence metabolism?
15
Δnuo uses the electrode
less efficiently than WT
16
strain [pyruvate] (mM) mmol e-/mmol lactate
WT 0.8±0.2 0.84±0.06
ΔnuoN 1.4±0.3 0.54±0.09
Metabolomics confirm
metabolic changes
17
Δnuo oxidizes substrate
less completely than WT
18
Electron transport chain
engineering alters energy flow
19
Combining electrodes and
synthetic biology
20
Shewanella oneidensis
• extracellular electron
transfer
• does not utilize sugar
• basic genetic tools
Escherichia coli
• no extracellular
electron transfer
• utilizes sugar
• highly developed
genetic systems
Combining electrodes and
synthetic biology
21
Shewanella oneidensis MR-1
E. coli wild-type
E. coli with Mtr
Jensen, TerAvest and Ajo-Franklin.
In preparation.
Advanced synbio methods
enhance Mtr-E. coli
V1.0 V2.0
22Goldbeck et al.
ACS Synthetic Biology, (2013).
Full pathway expression greatly
improves electron transfer
23Jensen, TerAvest and Ajo-Franklin.
In preparation.
Strain with full pathway survives
like wild-type E. coli
24TerAvest, Zajdel and Ajo-Franklin.
ChemElectroChem (2014).
Electrochemical performance of
E. coli is similar to Shewanella
25
Shewanella oneidensis
100-200 fA/cell
Escherichia coli
33 fA/cell
25% efficient 2.5% efficient
Watson and Logan.
Biotech and Bioeng (2009).
Liu et al.
Angew. Chem. (2011).
How does electron transfer impact
intracellular reactions?
26TerAvest, Zajdel and Ajo-Franklin.
ChemElectroChem (2014).
Current production is directly
connected to metabolism
27TerAvest, Zajdel and Ajo-Franklin.
ChemElectroChem (2014).
Mtr module shifts metabolism toward
more oxidized products
28
strain [formate] (μM) [ethanol] (μM)
ccm 44±13 64±0.6
cymA-mtr n.d. 40±3
TerAvest, Zajdel and Ajo-Franklin.
ChemElectroChem (2014).
Electrode interaction enhances
redox balance
29TerAvest, Zajdel and Ajo-Franklin,
ChemElectroChem (2014).
Mtr-modified E. coli produce
current with multiple substrates
30
Electrodes harvest reducing
equivalents from glucose
31
Synbio and electrodes relieve
redox balance constraints
32
Using microbial electrochemistry
and synbio to optimize bacteria
33
Dissection and redesign of the
bacterial respiratory powerhouse
34
Knowledge gained will enable
microbial electrosynthesis
35
CO2 +
Acetogens naturally perform
(slow) electrosynthesis
36Nevin, et al.
Mbio (2010).
Acetate production increased
20 times in 5 years
37Patil, et al.
ES&T (2015).
Removing barriers to
inward electron transfer
38Ross et al.
PLoS ONE (2011).
Inward electron transfer will
provide cofactors for synthesis
39
Artistic rendering of Shewanella by Cornell iGEM 2012