scholarly journals Identification of a pathway for electron uptake in Shewanella oneidensis

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Annette R. Rowe ◽  
Farshid Salimijazi ◽  
Leah Trutschel ◽  
Joshua Sackett ◽  
Oluwakemi Adesina ◽  
...  
Keyword(s):  
Scale Up ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Genetic Optimization ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Electrochemical Testing ◽  
Electron Transport Chains ◽  
Anaerobic Electron Transport ◽  
Electron Donation

AbstractExtracellular electron transfer (EET) could enable electron uptake into microbial metabolism for the synthesis of complex, energy dense organic molecules from CO2 and renewable electricity1–6. Theoretically EET could do this with an efficiency comparable to H2-oxidation7,8 but without the need for a volatile intermediate and the problems it causes for scale up9. However, significant gaps remain in understanding the mechanism and genetics of electron uptake. For example, studies of electron uptake in electroactive microbes have shown a role for the Mtr EET complex in the electroactive microbe Shewanella oneidensis MR-110–14, though there is substantial variation in the magnitude of effect deletion of these genes has depending on the terminal electron acceptor used. This speaks to the potential for previously uncharacterized and/or differentially utilized genes involved in electron uptake. To address this, we screened gene disruption mutants for 3667 genes, representing ≈99% of all nonessential genes, from the S. oneidensis whole genome knockout collection using a redox dye oxidation assay. Confirmation of electron uptake using electrochemical testing allowed us to identify five genes from S. oneidensis that are indispensable for electron uptake from a cathode. Knockout of each gene eliminates extracellular electron uptake, yet in four of the five cases produces no significant defect in electron donation to an anode. This result highlights both distinct electron uptake components and an electronic connection between aerobic and anaerobic electron transport chains that allow electrons from the reversible EET machinery to be coupled to different respiratory processes in S. oneidensis. Homologs to these genes across many different genera suggesting that electron uptake by EET coupled to respiration could be widespread. These gene discoveries provide a foundation for: studying this phenotype in exotic metal-oxidizing microbes, genetic optimization of electron uptake in S. oneidensis; and genetically engineering electron uptake into a highly tractable host like E. coli to complement recent advances in synthetic CO2 fixation15.

scholarly journals Identification of a Pathway for Electron Uptake in Shewanella oneidensis

2021 ◽  
Author(s):  
Annette R. Rowe ◽  
Farshid Salimijazi ◽  
Leah Trutschel ◽  
Joshua Sackett ◽  
Oluwakemi Adesina ◽  
...  
Keyword(s):  
Scale Up ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
E Coli ◽  
Electrochemical Testing ◽  
Electron Transport Chains ◽  
Molecular Machinery ◽  
Widespread Phenomenon ◽  
Anaerobic Electron Transport ◽  
Electron Donation

AbstractExtracellular electron transfer (EET) could enable electron uptake into microbial metabolism for the synthesis of complex, energy dense organic molecules from CO2 and renewable electricity1-6 . EET could do this with an efficiency comparable to H2 -oxidation7,8 but without the need for a volatile intermediate and the problems it causes for scale up9. However, naturally occurring electroactive organisms suffer from a number of technical drawbacks. Correcting these will require extensive knowledge of the genetics and mechanisms of electron uptake. To date, studies of electron uptake in electroactive microbes have focused on shared molecular machinery also used for anaerobic mineral reduction, like the Mtr EET complex in the electroactive microbe Shewanella oneidensis MR-110-14. However, this shared machinery cannot explain all features of electron uptake, hindering efforts to engineer electron uptake. To address this, we screened gene disruption mutants for 3,667 genes, representing ≈ 99% of all non-essential genes, from the S. oneidensis whole genome knockout collection using a redox dye oxidation assay as a proxy for electron uptake. Confirmation of electron uptake using electrochemical testing allowed us to identify five genes from S. oneidensis that are indispensable for electron uptake from a cathode. Knockout of each gene eliminates extracellular electron uptake, yet in 4 of the 5 cases produces no significant defect in electron donation to an anode, highlighting a distinct role for these loci in electron uptake vs. donation. This result highlights an electronic connection between aerobic and anaerobic electron transport chains that allow electrons from the reversible EET machinery to be coupled to different respiratory processes in S. oneidensis. Furthermore, we find homologs to these genes across many different genera suggesting that electron uptake by EET coupled to respiration could be a widespread phenomenon. These gene discoveries provide a foundation for studying this phenotype in exotic metal-oxidizing autotrophic microbes. Additionally, we anticipate that the characterization of these genes will allow for the genetic improvement of electron uptake in S. oneidensis; and genetically engineering electron uptake into a highly tractable host like E. coli to complement recent advances in synthetic CO2 fixation15.

scholarly journals Functional anaerobic electron transport linked to the reduction of nitrate and fumarate in membranes from Escherichia coli as demonstrated by quenching of atebrin fluorescence

1975 ◽  
Vol 152 (3) ◽  
pp. 655-659 ◽  
Author(s):  
B A Haddock ◽  
M W Kendall-Tobias
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Carbon Source ◽  
Electron Acceptor ◽  
Functional Organization ◽  
Terminal Electron Acceptor ◽  
Membrane Particles ◽  
Electron Transport Chains ◽  
Anaerobic Electron Transport ◽  
Energy Dependent

Measurements were made of energy-dependent quenching of atebrin fluorescence in membrane particles prepared from Escherichia coli grown anaerobically with glycerol as carbon source in the presence of either nitrate or fumarate. It is concluded that this technique can be used to study the functional organization of the anaerobic proton-translocating electron-transport chains that use nitrate or fumarate as terminal electron acceptor.

scholarly journals NADH dehydrogenases Nuo and Nqr1 contribute to extracellular electron transfer by Shewanella oneidensis MR-1 in bioelectrochemical systems

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Cody S. Madsen ◽  
Michaela A. TerAvest
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Growth Defect ◽  
Bioelectrochemical Systems ◽  
Terminal Electron Acceptor ◽  
Nadh Dehydrogenases ◽  
Level Of Understanding ◽  
High Level

Abstract Shewanella oneidensis MR-1 is quickly becoming a synthetic biology workhorse for bioelectrochemical technologies due to a high level of understanding of its interaction with electrodes. Transmembrane electron transfer via the Mtr pathway has been well characterized, however, the role of NADH dehydrogenases in feeding electrons to Mtr has been only minimally studied in S. oneidensis MR-1. Four NADH dehydrogenases are encoded in the genome, suggesting significant metabolic flexibility in oxidizing NADH under a variety of conditions. A strain lacking the two dehydrogenases essential for aerobic growth exhibited a severe growth defect with an anode (+0.4 VSHE) or Fe(III)-NTA as the terminal electron acceptor. Our study reveals that the same NADH dehydrogenase complexes are utilized under oxic conditions or with a high potential anode. Our study also supports the previously indicated importance of pyruvate dehydrogenase activity in producing NADH during anerobic lactate metabolism. Understanding the role of NADH in extracellular electron transfer may help improve biosensors and give insight into other applications for bioelectrochemical systems.

scholarly journals NADH dehydrogenases contribute to extracellular electron transfer byShewanella oneidensisMR-1 in bioelectrochemical systems

2019 ◽  
Author(s):  
Cody S. Madsen ◽  
Michaela A. TerAvest
Keyword(s):  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Extracellular Electron Transfer ◽  
Growth Defect ◽  
Bioelectrochemical Systems ◽  
Terminal Electron Acceptor ◽  
Nadh Dehydrogenases ◽  
Level Of Understanding ◽  
High Level

AbstractShewanella oneidensisMR-1 is quickly becoming a synthetic biology workhorse for bioelectrochemical technologies due to a high level of understanding of its interaction with electrodes. Transmembrane electron transfer via the Mtr pathway has been well characterized, however, the role of NADH dehydrogenases in feeding electrons to Mtr has been only minimally studied inS. oneidensisMR-1. Four NADH dehydrogenases are encoded in the genome, suggesting significant metabolic flexibility in oxidizing NADH under a variety of conditions. Strains containing in-frame deletions of each of these dehydrogenases were grown in anodic bioelectrochemical systems with N-acetylglucosamine or D,L-lactate as the carbon source to determine impact on extracellular electron transfer. A strain lacking the two dehydrogenases essential for aerobic growth exhibited a severe growth defect with an anode (+0.4 VSHE) or Fe(III)-NTA as the terminal electron acceptor. Our study reveals that the same NADH dehydrogenase complexes are utilized under oxic conditions or with a high potential anode. Understanding the role of NADH in extracellular electron transfer may help improve biosensors and give insight into other applications for bioelectrochemical systems.TOC Graphic

scholarly journals Tailored extracellular electron transfer pathways enhance the electroactivity of Escherichia coli

2021 ◽  
Author(s):  
Mohammed Mouhib ◽  
Melania Reggente ◽  
Lin Li ◽  
Nils Schuergers ◽  
Ardemis Anoush Boghossian
Keyword(s):  
Escherichia Coli ◽  
Electron Transfer ◽  
Shewanella Oneidensis ◽  
Electrical Current ◽  
Extracellular Electron Transfer ◽  
Organic Substrates ◽  
Transfer Rates ◽  
Electron Shuttling ◽  
E Coli ◽  
Electron Transfer Pathways

Extracellular electron transfer (EET) engineering in Escherichia coli holds great potential for bioremediation, energy and electrosynthesis applications fueled by readily available organic substrates. Due to its vast metabolic capabilities and availability of synthetic biology tools to adapt strains to specific applications, E. coli is of advantage over native exoelectrogens, but limited in electron transfer rates. We enhanced EET in engineered strains through systematic expression of electron transfer pathways differing in cytochrome composition, localization and origin. While a hybrid pathway harboring components of an E. coli nitrate reductase and the Mtr complex from the exoelectrogen Shewanella oneidensis MR-1 enhanced EET, the highest efficiency was achieved by implementing the complete Mtr pathway from S. oneidensis MR1 in E. coli. We show periplasmic electron shuttling through overexpression of a small tetraheme cytochrome to be central to the electroactivity of this strain, leading to enhanced degradation of the pollutant methyl orange and significantly increased electrical current to graphite electrodes.

scholarly journals Complete biosynthesis of a sulfated chondroitin in Escherichia coli

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Abinaya Badri ◽  
Asher Williams ◽  
Adeola Awofiranye ◽  
Payel Datta ◽  
Ke Xia ◽  
...  
Keyword(s):  
Chondroitin Sulfate ◽  
Scale Up ◽  
Production Methods ◽  
E Coli ◽  
Microbial Cell Factories ◽  
Cell Factories ◽  
Microbial Product ◽  
Dry Cell Weight ◽  
One Step ◽  
Dry Cell

AbstractSulfated glycosaminoglycans (GAGs) are a class of important biologics that are currently manufactured by extraction from animal tissues. Although such methods are unsustainable and prone to contamination, animal-free production methods have not emerged as competitive alternatives due to complexities in scale-up, requirement for multiple stages and cost of co-factors and purification. Here, we demonstrate the development of single microbial cell factories capable of complete, one-step biosynthesis of chondroitin sulfate (CS), a type of GAG. We engineer E. coli to produce all three required components for CS production–chondroitin, sulfate donor and sulfotransferase. In this way, we achieve intracellular CS production of ~27 μg/g dry-cell-weight with about 96% of the disaccharides sulfated. We further explore four different factors that can affect the sulfation levels of this microbial product. Overall, this is a demonstration of simple, one-step microbial production of a sulfated GAG and marks an important step in the animal-free production of these molecules.

scholarly journals Promiscuous Cross-seeding between Bacterial Amyloids Promotes Interspecies Biofilms

2012 ◽  
Vol 287 (42) ◽  
pp. 35092-35103 ◽  
Author(s):  
Yizhou Zhou ◽  
Daniel Smith ◽  
Bryan J. Leong ◽  
Kristoffer Brännström ◽  
Fredrik Almqvist ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shewanella Oneidensis ◽  
Bacterial Attachment ◽  
Surface Attachment ◽  
E Coli ◽  
Amyloid Aggregates ◽  
Functional Amyloids ◽  
Biofilm Development ◽  
Distant Homolog

Amyloids are highly aggregated proteinaceous fibers historically associated with neurodegenerative conditions including Alzheimers, Parkinsons, and prion-based encephalopathies. Polymerization of amyloidogenic proteins into ordered fibers can be accelerated by preformed amyloid aggregates derived from the same protein in a process called seeding. Seeding of disease-associated amyloids and prions is highly specific and cross-seeding is usually limited or prevented. Here we describe the first study on the cross-seeding potential of bacterial functional amyloids. Curli are produced on the surface of many Gram-negative bacteria where they facilitate surface attachment and biofilm development. Curli fibers are composed of the major subunit CsgA and the nucleator CsgB, which templates CsgA into fibers. Our results showed that curli subunit homologs from Escherichia coli, Salmonella typhimurium LT2, and Citrobacter koseri were able to cross-seed in vitro. The polymerization of Escherichia coli CsgA was also accelerated by fibers derived from a distant homolog in Shewanella oneidensis that shares less than 30% identity in primary sequence. Cross-seeding of curli proteins was also observed in mixed colony biofilms with E. coli and S. typhimurium. CsgA was secreted from E. coli csgB− mutants assembled into fibers on adjacent S. typhimurium that presented CsgB on its surfaces. Similarly, CsgA was secreted by S. typhimurium csgB− mutants formed curli on CsgB-presenting E. coli. This interspecies curli assembly enhanced bacterial attachment to agar surfaces and supported pellicle biofilm formation. Collectively, this work suggests that the seeding specificity among curli homologs is relaxed and that heterogeneous curli fibers can facilitate multispecies biofilm development.

Impact of Graphitic Structures in Pyrogenic Carbon on Microbial Reduction of Ferrihydrite

2021 ◽  
Author(s):  
wentao yu ◽  
baoliang chen
Keyword(s):  
Electron Transfer ◽  
Pyrolysis Temperature ◽  
Shewanella Oneidensis ◽  
Exchange Capacity ◽  
Microbial Reduction ◽  
Systematic Evaluation ◽  
Extracellular Electron Transfer ◽  
Pyrogenic Carbon ◽  
The Impact

<p>Pyrogenic carbon plays important roles in microbial reduction of ferrihydrite by shuttling electrons in the extracellular electron transfer (EET) processes. Despite its importance, a full assessment on the impact of graphitic structures in pyrogenic carbon on microbial reduction of ferrihydrite has not been conducted. This study is a systematic evaluation of microbial ferrihydrite reduction by Shewanella oneidensis MR-1 in the presence of pyrogenic carbon with various graphitization extents. The results showed that the rates and extents of microbial ferrihydrite reduction were significantly enhanced in the presence of pyrogenic carbon, and increased with increasing pyrolysis temperature. Combined spectroscopic and electrochemical analyses suggested that the rate of microbial ferrihydrite reduction were dependent on the electrical conductivity of pyrogenic carbon (i.e., graphitization extent), rather than the electron exchange capacity. The key role of graphitic structures in pyrogenic carbon in mediating EET was further evidenced by larger microbial electrolysis current with pyrogenic carbon prepared at higher pyrolysis temperatures. This study provides new insights into the electron transfer in the pyrogenic carbon-mediated microbial reduction of ferrihydrite.</p>

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