In Situ Optical Quantification of Extracellular Electron Transfer using Plasmonic Metal Oxide Nanocrystals

2021 ◽  
Author(s):  
Austin Graham ◽  
Stephen Gibbs ◽  
Camila A. Saez Cabezas ◽  
Yongdan Wang ◽  
Allison Green ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Metal Oxide ◽  
Extracellular Electron Transfer

scholarly journals In Situ Optical Quantification of Extracellular Electron Transfer from Shewanella oneidensis using Plasmonic Metal Oxide Nanocrystals

2020 ◽  
Author(s):  
Austin J. Graham ◽  
Stephen L. Gibbs ◽  
Camila A. Saez Cabezas ◽  
Yongdan Wang ◽  
Allison M. Green ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Metal Oxide ◽  
Shewanella Oneidensis ◽  
Genetic Circuit ◽  
Extracellular Electron Transfer ◽  
Materials Synthesis ◽  
Electron Model ◽  
Time Resolved ◽  
Optical Extinction

AbstractExtracellular electron transfer (EET) is a critical form of microbial metabolism that enables respiration on a variety of inorganic substrates, including metal oxides. For this reason, engineering EET processes has garnered significant interest for applications ranging from bioelectronics to materials synthesis. These applications require a strong understanding of electron flux from EET-relevant microbes. However, quantifying current generated by electroactive bacteria has been predominately limited to biofilms formed on electrodes, which require long incubation times, electrode colonization, and convolute contributions to EET from planktonic cells. To address this, we developed a platform for quantifying time-resolved EET flux from cell suspensions using aqueous dispersions of plasmonic tin-doped indium oxide nanocrystals. Tracking the change in optical extinction during electron transfer and fitting the optical response to a free electron model enabled quantification of current generation and electron transfer rate constants from planktonic Shewanella oneidensis cultures. Using this method, we differentiated between starved and actively respiring S. oneidensis, and between cells of varying genotype using an EET knockout strain. In addition, we quantified current production ranging from 0.12 – 0.68 fA • cell−1 from S. oneidensis cells engineered to differentially express a key EET gene using an inducible genetic circuit. Overall, our results validate the utility of colloidally stable plasmonic metal oxide nanocrystals as quantitative biosensors in native biological environments and contribute to a fundamental understanding of planktonic S. oneidensis electrophysiology using simple in situ spectroscopy.

scholarly journals In Situ Electrochemical Studies of the Terrestrial Deep Subsurface Biosphere at the Sanford Underground Research Facility, South Dakota, USA

2019 ◽  
Author(s):  
Yamini Jangir ◽  
Amruta A. Karbelkar ◽  
Nicole M. Beedle ◽  
Laura A. Zinke ◽  
Greg Wanger ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Microbial Populations ◽  
Extracellular Electron Transfer ◽  
Research Facility ◽  
Deep Subsurface ◽  
Electrochemically Active ◽  
Mineral Interfaces ◽  
Terrestrial Subsurface ◽  
Sanford Underground Research Facility

ABSTRACTThe terrestrial deep subsurface is host to significant and diverse microbial populations. However, these microbial populations remain poorly characterized, partially due to the inherent difficulty of sampling,in situstudies, and isolating of thein situmicrobes. Motivated by the ability of microbes to gain energy from redox reactions at mineral interfaces, we here presentin situelectrochemical colonization (ISEC) as a method to directly study microbial electron transfer activity and to enable the capture and isolation of electrochemically active microbes. We installed a potentiostatically controlled ISEC reactor containing four working electrodes 1500 m below the surface at the Sanford Underground Research Facility. The working electrodes were poised at different redox potentials, spanning anodic to cathodic, to mimic energy-yielding mineral reducing and oxidizing reactions predicted to occur at this site. We present a 16S rRNA analysis of thein situelectrode-associated microbial communities, revealing the dominance of novel bacterial lineages under cathodic conditions. We also demonstrate that thein situelectrodes can be further used for downstream electrochemical laboratory enrichment and isolation of novel strains. Using this workflow, we isolatedBacillus,Anaerospora,Comamonas,Cupriavidus, andAzonexusstrains from the electrode-attached biomass. Finally, the extracellular electron transfer activity of the electrode-oxidizingComamonasstrain (isolated at −0.19 V vs. SHE and designated WE1-1D1) and the electrode-reducingBacillusstrain (isolated at +0.53 V vs. SHE and designated WE4-1A1-BC) were confirmed in electrochemical reactors. Our study highlights the utility ofin situelectrodes and electrochemical enrichment workflows to shed light on microbial activity in the deep terrestrial subsurface.SIGNIFICANCEA large section of microbial life resides in the deep subsurface, but an organized effort to explore this deep biosphere has only recently begun. A detailed characterization of the resident microbes remains scientifically and technologically challenging due to difficulty in access, sampling, and emulating the complex interactions and energetic landscapes of subsurface communities with standard laboratory techniques. Here we describe an in situ approach that exploits the ability of many microbes to perform extracellular electron transfer to/from solid surfaces such as mineral interfaces in the terrestrial subsurface. By deploying and controlling the potential of in situ electrodes 4850 ft below the surface at the Sanford Underground Research Facility (South Dakota, USA), we highlight the promise of electrochemical techniques for studying active terrestrial subsurface microbial communities and enabling the isolation of electrochemically active microbes.

Facilitated extracellular electron transfer of Geobacter sulfurreducens biofilm with in situ formed gold nanoparticles

2018 ◽  
Vol 108 ◽  
pp. 20-26 ◽  
Author(s):  
Man Chen ◽  
Xiaofang Zhou ◽  
Xing Liu ◽  
Raymond Jianxiong Zeng ◽  
Fang Zhang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Electron Transfer ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer

In Situ Autofluorescence Spectroelectrochemistry for the Study of Microbial Extracellular Electron Transfer

2017 ◽  
Vol 4 (10) ◽  
pp. 2515-2519 ◽  
Author(s):  
Igor Schmidt ◽  
Alexander Pieper ◽  
Hilke Wichmann ◽  
Boyke Bunk ◽  
Katharina Huber ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Extracellular Electron Transfer

scholarly journals Conversion of Methanol on Rutile TiO2 (110) and Tungsten Oxide Clusters: 2. The Role of Defects and Electron Transfer in Bifunctional Oxidic Photocatalysts

2021 ◽  
Author(s):  
Lars Mohrhusen ◽  
Jessica Kräuter ◽  
Katharina Al-Shamery
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Metal Oxide ◽  
Tungsten Oxide ◽  
Organic Compounds ◽  
Uv Irradiation ◽  
Organic P ◽  
Rutile Tio2 ◽  
Metal Oxide Surfaces

The photochemical conversion of organic compounds on tailored transition metal oxide surfaces by (UV) irradiation has found wide applications ranging from the production of chemicals to the degradation of organic...

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