Diffusion-Based Recycling of Flavins Allows <i>Shewanella oneidensis</i> MR-1 To Yield Energy from Metal Reduction Across Physical Separations

Michelson, Kyle; Alcalde, Reinaldo E.; Sanford, Robert A.; Valocchi, Albert J.; Werth, Charles J.

doi:10.1021/acs.est.8b04718

Cited by 31 publications

(24 citation statements)

References 43 publications

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“…As ATP represents the energy stored from the intracellular redox reactions of bacteria 22 , the metabolic activity of the cells with/without the CDs' addition was further evaluated by an ATP assay ( Fig. 6b).…”

Section: Resultsmentioning

confidence: 99%

Carbon dots-fed Shewanella oneidensis MR-1 for bioelectricity enhancement

et al. 2020

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Bioelectricity generation, by Shewanella oneidensis (S. oneidensis) MR-1, has become particularly alluring, thanks to its extraordinary prospects for energy production, pollution treatment, and biosynthesis. Attempts to improve its technological output by modification of S. oneidensis MR-1 remains complicated, expensive and inefficient. Herein, we report on the augmentation of S. oneidensis MR-1 with carbon dots (CDs). The CDs-fed cells show accelerated extracellular electron transfer and metabolic rate, with increased intracellular charge, higher adenosine triphosphate level, quicker substrate consumption and more abundant extracellular secretion. Meanwhile, the CDs promote cellular adhesion, electronegativity, and biofilm formation. In bioelectrical systems the CDs-fed cells increase the maximum current value, 7.34 fold, and power output, 6.46 fold. The enhancement efficacy is found to be strongly dependent on the surface charge of the CDs. This work demonstrates a simple, costeffective and efficient route to improve bioelectricity generation of S. oneidensis MR-1, holding promise in all relevant technologies.

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Section: Resultsmentioning

confidence: 99%

Carbon dots-fed Shewanella oneidensis MR-1 for bioelectricity enhancement

et al. 2020

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“…The use of iron oxides as terminal electron acceptors in anaerobic microbial respiration is central to biogeochemical element cycling and pollutant transformations in many suboxic and anoxic environments ( 1 – 6 ). To ensure efficient electron transfer to solid-phase ferric iron, Fe(III), at circumneutral pH, metal-reducing microorganisms from diverse phylae use dissolved extracellular electron shuttle (EES), including quinones ( 7 – 9 ), flavins ( 10 – 16 ), and phenazines ( 17 – 19 ), to transfer two electrons per EES molecule from the respiratory chain proteins in the outer membrane of the microbial cell to the iron oxide ( 17 , 20 , 21 ). The oxidized EES can diffuse back to the cell surface for rereduction, thereby completing the catalytic redox cycle involving the EES.…”

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confidence: 99%

Thermodynamic controls on rates of iron oxide reduction by extracellular electron shuttles

Aeppli

Giroud

Vranic

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Anaerobic microbial respiration in suboxic and anoxic environments often involves particulate ferric iron (oxyhydr-)oxides as terminal electron acceptors. To ensure efficient respiration, a widespread strategy among iron-reducing microorganisms is the use of extracellular electron shuttles (EES) that transfer two electrons from the microbial cell to the iron oxide surface. Yet, a fundamental understanding of how EES–oxide redox thermodynamics affect rates of iron oxide reduction remains elusive. Attempts to rationalize these rates for different EES, solution pH, and iron oxides on the basis of the underlying reaction free energy of the two-electron transfer were unsuccessful. Here, we demonstrate that broadly varying reduction rates determined in this work for different iron oxides and EES at varying solution chemistry as well as previously published data can be reconciled when these rates are instead related to the free energy of the less exergonic (or even endergonic) first of the two electron transfers from the fully, two-electron reduced EES to ferric iron oxide. We show how free energy relationships aid in identifying controls on microbial iron oxide reduction by EES, thereby advancing a more fundamental understanding of anaerobic respiration using iron oxides.

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“…For example, S. oneidensis can facilitate electron transfer directly via outer membrane c-type cytochromes (c-Cyts) in contact with iron (oxyhyr)oxides, or indirectly via electron shuttles that can diffuse between c-Cyts and ferric (oxyhydr)oxides to mediate electron transfer . Recent work has shown that naturally occurring electron shuttles can diffuse over micrometer to centimeter distances to transfer electrons, , and for centimeter-scale mass transfer distances the iron (oxyhydr)oxide reduction rates will likely be diffusion controlled.…”

Section: Discussionmentioning

confidence: 99%

Biological Reduction of Ferrihydrite with Silica Addition: Rates and Controlling Mechanisms

Gong

Zhang

et al. 2021

ACS Earth Space Chem.

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Si-incorporated ferrihydrite (SiFh) is ubiquitous in nature, and Fe(III) reactivity within such minerals is relevant to a number of important biogeochemical reactions, including soil organic carbon turnover and pollutant oxidation. Herein, reduction of SiFh with varying Si/Fe molar ratios was investigated and rates and controlling mechanisms were explored. Results showed that SiFh first-order reduction rates increased from 0.038 to 0.113 day–1 as the Si/Fe ratio increases from 0 to 0.444, respectively. As expected, the reduction rate constant increases with decreasing SiFh crystallinty. However, it increases with decreasing SiFh surface area (304.7–188.9 m2 g–1) and standard reduction potential (0.897–0.829 V). The lack of correlation with surface areas or thermodynamic favorability motivated measurement of electron transfer rate constants using mediated electrochemical reduction (MER), and these values increased with Si/Fe ratios of SiFh. This suggests that electron transfer rates to SiFh surfaces may limit SiFh reduction rates by Shewanella oneidensisMR-1 and that electron transfer rates increase with decreasing SiFh crystallinity. The results have implications for understanding rates of metal oxide reduction and associated rates of organic carbon, nutrient, and pollutant oxidation in natural environments where silica is common.

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Diffusion-Based Recycling of Flavins Allows Shewanella oneidensis MR-1 To Yield Energy from Metal Reduction Across Physical Separations

Cited by 31 publications

References 43 publications

Carbon dots-fed Shewanella oneidensis MR-1 for bioelectricity enhancement

Carbon dots-fed Shewanella oneidensis MR-1 for bioelectricity enhancement

Thermodynamic controls on rates of iron oxide reduction by extracellular electron shuttles

Biological Reduction of Ferrihydrite with Silica Addition: Rates and Controlling Mechanisms

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