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Electronic, electrochemical, and spintronic characterization of bacterial electron transport
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Electronic, electrochemical, and spintronic characterization of bacterial electron transport
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Content
v
Table of Contents
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background: the Systems of Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Extracellular Electron Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.2 Shewanella oneidensis: Physiology and Key Discoveries . . . . . . . . . . . . . 3
1.1.3 Geobacter sulfurreducens: Physiology and Key Discoveries . . . . . . . . . . . 7
1.1.4 Chirality and the Chiral Induced Spin Selectivity Effect. . . . . . . . . . . . . . 8
1.1.5 Long-Distance Electron Transport in Biology . . . . . . . . . . . . . . . . . . 11
1.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2.1 Atomic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2.2 Scanning Tunneling Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.2.3 Electrochemical Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.3 Overview of Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 2: Light induced deposition of Shewanella facilitates characterization of electron
transport mechanisms in biofilms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.2.1 Bioreactor Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.2.2 Fabrication of Custom Interdigitated Array Electrodes . . . . . . . . . . . . . . 33
2.2.3 Cyclic Voltammetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.2.4 Electrochemical Gating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.2.5 Strain Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.2.6 Cell Culturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.2.7 Determination of a Define Biofilm Geometry . . . . . . . . . . . . . . . . . . 36
2.2.8 Crystal Violet Staining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
vi
2.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.3.1 Overview of Wild-Type Patterning Work . . . . . . . . . . . . . . . . . . . . 37
2.3.2 Distance Dependent Conduction in Wild-Type Patterned Biofilms . . . . . . . 38
2.3.3 Electrochemical Interrogations of Biofilms with Cytochrome Expression
Tuned by Vanillic Acid Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3.4 Periplasmic Cytochrome Deficient Biofilms . . . . . . . . . . . . . . . . . . . 46
2.3.5 Using the iLight Sensor to Exert Optogenetic Control of Cytochrome
Expression in Shewanella Biofilms . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Chapter 3: Investigation of Chiral Induced Spin Selectivity in Isolated Shewanella Proteins . 68
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.2 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.2.1 Protein Purification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
3.2.2 Protein Monolayer Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.2.3 Protein Monolayer Characterization by AFM . . . . . . . . . . . . . . . . . . 75
3.2.4 Magnetic Heterostructure Fabrication . . . . . . . . . . . . . . . . . . . . . . 75
3.2.5 Magnetic Conductive AFM Experiment . . . . . . . . . . . . . . . . . . . . . 76
3.2.6 PMIRRAS Characterization of STC-M . . . . . . . . . . . . . . . . . . . . . . 76
3.2.7 Protein Electrochemical Characterization . . . . . . . . . . . . . . . . . . . . 77
3.2.8 STM Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.9 Hall Device Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.2.10 Hall Voltage Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.2.11 Substrate Characterization by Polar Magneto-optic Kerr Effect Measurement . 81
3.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Chapter 4: Magnetic Field Dependent Respiration Rates in Geobacter Biofilms . . . . . . . 89
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
4.2.1 G. sulfurreducens Culturing. . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
4.2.2 Reactor Construction and Preparation . . . . . . . . . . . . . . . . . . . . . . 90
4.2.3 G. sulfurreducens Electrochemical Pre-growth . . . . . . . . . . . . . . . . . . 92
4.2.4 Electrode Fabrication and Preparation . . . . . . . . . . . . . . . . . . . . . . 93
4.2.5 Magnetic Field Dependent Chronoamperometry . . . . . . . . . . . . . . . . . 94
4.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Chapter 5: Characterization of Electron Transport in Cable Bacteria . . . . . . . . . . . . 104
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.2 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
5.2.1 Sample Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
5.2.2 Sample Processing, Incubation, and Preparation . . . . . . . . . . . . . . . . 107
5.2.3 Atomic Force Microscopy Under Inert Atmosphere . . . . . . . . . . . . . . 108
vii
5.2.4 Electrostatic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . 110
5.2.5 Conductive AFM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
5.2.6 Frequency Modulated Kelvin Probe Force Microscopy . . . . . . . . . . . . . 113
5.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
5.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Chapter 6: Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Appendix A: Media Recipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
A.1 S. oneidensis Minimal Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
A.2 S. oneidensis Vitamins (1000X Stock) . . . . . . . . . . . . . . . . . . . . . . . . 148
A.3 S. oneidensis Minerals (100X Stock) . . . . . . . . . . . . . . . . . . . . . . . . . 149
A.4 S. oneidensis Amino Acids Solution (100X Stock) . . . . . . . . . . . . . . . . . . 150
Abstract (if available)
Abstract
All biological energy conversion strategies require electron transfer in some form. To gain a competitive advantage and survive in environments devoid of soluble electron acceptors, some microbes have adapted the ability to transfer electrons to external abiotic surfaces. This extracellular electron transfer (EET) is achieved through a suite of iron-containing proteins dubbed "multiheme cytochromes" which form an extended electron transfer network beginning at the inner membrane, extending into the periplasm, through the outer membrane, and along the cell surface. Study of these electron conduits has broader implications than EET for biological electron transfer. The study of EET capable organisms has extended the known length scales of biological electron transfer by many orders of magnitude, and recent results have shown that electron transport in multiheme cytochromes is spin selective. Thus the fields of Long-Distance Electron Transport (LDET) and Chiral Induced Spin Selectivity (CISS) are intermingled with the field of EET.
While the CISS effect is well established in a variety of chiral molecules, only one previous study has looked at multiheme cytochromes implicated in EET, and that study was limited to cell surface cytochromes. I investigated the CISS effect in two key components of the EET pathway in S. oneidensis: the periplasmic cytochrome STC and the membrane-spanning cytochrome MtrA. The measurements show higher spin selectivity in MtrA than STC, and demonstrate that, beyond the cell surface reductases, spin filtering is exhibited by multiple EET proteins that span the cell envelope.
As the suite of cytochromes confirmed to be spin selective expands, it is important to note that the biological impact of CISS on electron transfer by living cells has not been verified. I conducted preliminary measurements which represent the first evidence for in vivo spin selectivity. Magnetochronoamperometry measurements of G. sulfurreducens biofilms show that the respiration rates of these cells respond on the order of seconds to changes in the orientation of an out-of-plane magnetic field.
To study long-distance biofilm conduction and how different cytochromes throughout the cell envelope affect EET, I use electrochemistry to investigate the conductive properties and electrode activity of light-deposited S. oneidensis wild-type and cytochrome deficient biofilms.
While S. oneidensis performs LDET on the scale of many microns, recently discovered cable bacteria form multicellular communities with centimeter scale electron transport. To address the mechanism of LDET in cable bacteria, we use scanning probe techniques to achieve nanometer scale mapping of local electronic properties of conducting structures. I share preliminary electrostatic force microscopy and Kelvin probe force microscopy measurements on cable bacteria samples collected from three sites in Southern California.
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Asset Metadata
Creator
Niman, Christina
(author)
Core Title
Electronic, electrochemical, and spintronic characterization of bacterial electron transport
School
College of Letters, Arts and Sciences
Degree
Doctor of Philosophy
Degree Program
Physics
Degree Conferral Date
2023-08
Publication Date
06/27/2023
Defense Date
06/20/2023
Publisher
University of Southern California
(original),
University of Southern California. Libraries
(digital)
Tag
cable bacteria,chiral induced spin selectivity,extracellular electron transport,geobacter,long-distance electron transport,OAI-PMH Harvest,Shewanella
Format
theses
(aat)
Language
English
Contributor
Electronically uploaded by the author
(provenance)
Advisor
El-Naggar, Moh (
committee chair
), Boedicker, James (
committee member
), Finkel, Steve (
committee member
), Kresin, Vitaly (
committee member
)
Creator Email
colechri@usc.edu
Permanent Link (DOI)
https://doi.org/10.25549/usctheses-oUC113259818
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UC113259818
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etd-NimanChris-11996.pdf (filename)
Legacy Identifier
etd-NimanChris-11996
Document Type
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Format
theses (aat)
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Niman, Christina
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20230630-usctheses-batch-1059
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University of Southern California
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University of Southern California Dissertations and Theses
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The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright.
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Repository Email
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Tags
cable bacteria
chiral induced spin selectivity
extracellular electron transport
geobacter
long-distance electron transport
Shewanella