A metabolic-activity-detecting approach to life detection: Restoring a chemostat from stop-feeding using a rapid bioactivity assay

Li, Shiue-Lin; Bai, Ming-Der; Hsiao, Chia-Jung; Cheng, Sheng-Shung; Nealson, Kenneth H.

doi:10.1016/j.bioelechem.2017.08.001

Cited by 8 publications

(5 citation statements)

References 54 publications

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“…S13A). However, the mediating [Fe(CN)6] 4-/3can freely diffuse to bulk electrolyte, therefore, one symmetric CV was observed (Li et al 2017). A similar experiment was conducted with CV in 1 mM [Fe(CN)6] 3and 9 mM glucose at 50 mV s -1 , but [Fe(CN)6] 4-/3were imprisoned in the small space between MR-1 layer and the electrode surface.…”

Section: The Formation Of Palladium Nanoparticles On Mr-1 Block the [Fe(cn)6] 4electrocatalytic Oxidationmentioning

confidence: 93%

“…[Fe(CN)6] 4-/3can act as a redox mediator in some bioelectrochemical process due to high reversibility (Li et al 2017;Li et al 2018), like an endogenous redox mediator riboflavin secreted by Shewanella (Marsili et al 2008).…”

Section: The Formation Of Palladium Nanoparticles On Mr-1 Block the [Fe(cn)6] 4electrocatalytic Oxidationmentioning

confidence: 99%

“…In (Li et al 2017), microbes including EAB colonizing on the PV layer need to employ mediators [Fe(CN)6] 3to communicate with the electrode (Fig. S13A).…”

Section: The Formation Of Palladium Nanoparticles On Mr-1 Block the [Fe(cn)6] 4electrocatalytic Oxidationmentioning

confidence: 99%

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Electrons selective uptake of a metal-reducing bacterium Shewanella oneidensis MR-1 from ferrocyanide

Zheng

Xiao

et al. 2019

Biosensors and Bioelectronics

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The extracellular electron transfer of Shewanella oneidensis MR-1 (MR-1) has been extensively studied due to the importance of the biosensors and energy applications of bioelectrochemical systems. However, the oxidation of metal compounds by MR-1, which represents the inward extracellular electron transfer from extracellular electron donors into the microbe, is barely understood. In this study, MR-1 immobilized on an electrode electrocatalyzes the oxidation of [Fe(CN) 6] 4to [Fe(CN)6] 3efficiently and selectively. The selectivity depends on midpoint potential and overall charge(s) of redox molecules. Among 12 investigated redox molecules, the negatively charged molecules with high midpoint potentials, i.e., [Ru(CN)6] 4and [Fe(CN)6] 4-, show strong electrocatalysis. Neither reference bacteria (Escherichia coli K-12 nor Streptococcus mutans) electrocatalyze the oxidation of [Fe(CN)6] 4-. The electrocatalysis decays when MR-1 is covered with palladium nanoparticles presumptively involved with cytochromes c. However, cytochromes c MtrC and OmcA on MR-1 do not play an essential role in this process. The results support a model that [Fe(CN)6] 4donor electrons to MR-1 by interacting with undiscovered active sites and the electrons are subsequently transferred to the electrode through the mediating effect of [Fe(CN)6] 4-/3-. The selective electron uptake by MR-1 provides valuable insights into the fundamental insights of the applications of bioelectrochemical systems and the detection of specific redox molecules.

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Section: The Formation Of Palladium Nanoparticles On Mr-1 Block the [Fe(cn)6] 4electrocatalytic Oxidationmentioning

confidence: 93%

Section: The Formation Of Palladium Nanoparticles On Mr-1 Block the [Fe(cn)6] 4electrocatalytic Oxidationmentioning

confidence: 99%

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Electrons selective uptake of a metal-reducing bacterium Shewanella oneidensis MR-1 from ferrocyanide

Zheng

Xiao

et al. 2019

Biosensors and Bioelectronics

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“…One distinctive observation found in this study that is contradictive to previous electrochemical results [ 30 ] is that the riboflavin boosted the electron transfer rates better than the ferricyanide did with 7 mg mL −1 GO used as the electron acceptor, even when the concentrations of them were far from each other (i.e., the 5 μM riboflavin against 2.5 mM ferricyanide). This finding can be supported via thermodynamic consideration: the redox potential of rGO was reported to be 44 mV (vs. the standard hydrogen electrode, SHE [ 24 ]), which may not favorably receive the electrons from ferrocyanide (i.e., the reduced form of ferricyanide, possessing the redox potential of +300 mV vs. SHE), but may from riboflavin (−300 mV vs. SHE [ 54 ]). The flavin compounds, widespread secretions among gammaproteobacteria [ 48 ], have been reported as an EET booster in many studies, enhancing current production on microbial electrodes [ 47 ] and serving as a crucial role in solid-mineral reduction, which cannot be executed solely by outer-membrane cytochromes [ 55 ] in some cases.…”

Section: Discussionmentioning

confidence: 99%

Investigating the Extracellular-Electron-Transfer Mechanisms and Kinetics of Shewanella decolorationis NTOU1 Reducing Graphene Oxide via Lactate Metabolism

Liou

Hsieh

et al. 2023

Bioengineering

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Microbial graphene oxide reduction is a developing method that serves to reduce both production costs and environmental impact in the synthesis of graphene. This study demonstrates microbial graphene oxide reduction using Shewanella decolorationis NTOU1 under neutral and mild conditions (pH = 7, 35 °C, and 1 atm). Graphene oxide (GO) prepared via the modified Hummers’ method is used as the sole solid electron acceptor, and the characteristics of reduced GO (rGO) are investigated. According to electron microscopic images, the surface structure of GO was clearly changed from smooth to wrinkled after reduction, and whole cells were observed to be wrapped by GO/rGO films. Distinctive appendages on the cells, similar to nanowires or flagella, were also observed. With regard to chemical-bonding changes, after a 24-h reaction of 1 mg mL−1, GO was reduced to rGO, the C/O increased from 1.4 to 3.0, and the oxygen-containing functional groups of rGO were significantly reduced. During the GO reduction process, the number of S. decolorationis NTOU1 cells decreased from 1.65 × 108 to 1.03 × 106 CFU mL−1, indicating the bactericide effects of GO/rGO. In experiments adding consistent concentrations of initial bacteria and lactate, it was shown that with the increase of GO additions (0.5–5.0 mg mL−1), the first-order reaction rate constants (k) of lactate metabolism and acetate production increased accordingly; in experiments adding consistent concentrations of initial bacteria and GO but different lactate levels (1 to 10 mM), the k values of lactate metabolism did not change significantly. The test results of adding different electron transfer mediators showed that riboflavin and potassium ferricyanide were able to boost GO reduction, whereas 2,6-dimethoxy-1,4-benzoquinone and 2,6-dimethyl benzoquinone completely eliminated bacterial activity.

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“…Diffusive electron shuttles used as mediators need some essential properties, including high diffusion coefficients, rapid electron transfer, sustainability in repeated redox turnover, and non-cytotoxicity (Bullen et al, 2006). The soluble electron shuttles usually work as transferring across the porin to the cell interior (Ikeda, 2012) in order to bring the electrons out from the internal redox protein (e.g., nicotinamide adenine dinucleotide dehydrogenase, NDH, Li et al, 2017) to the outer electron acceptors, or directly exchange electrons with the outer membrane cytochromes (OMCs, Coursolle et al, 2010). Moreover, recent studies indicated that electron shuttles (i.e., flavin mononucleotide and riboflavin) might interact with OMC by direct bonding, creating the shortest physical distance to favor the electron flow (Okamoto et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Chemical Characteristics of Electron Shuttles Affect Extracellular Electron Transfer: Shewanella decolorationis NTOU1 Simultaneously Exploiting Acetate and Mediators

Wang

Chen

et al. 2019

Front. Microbiol.

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In the present study, we found that our isolate Shewanella decolorationis NTOU1 is able to degrade acetate under anaerobic condition with concomitant implementation of extracellular electron transfer (EET). With +0.63 V (vs. SHE) poised on the anode, in a 72-h experiment digesting acetate, only 2 mM acetate was consumed, which provides 6% of the electron equivalents derived from the initial substrate mass to support biomass (5%) and current generation (1%). To clarify the effects on EET of the addition of electron-shuttles, riboflavin, anthraquinone-2,6-disulfonate (AQDS), hexaammineruthenium, and hexacyanoferrate were selected to be spiked into the electrochemical cell in four individual experiments. It was found that the mediators with proton-associated characteristics (i.e., riboflavin and AQDS) would not enhance current generation, but the metal-complex mediators (i.e., hexaammineruthenium, and hexacyanoferrate) significantly enhanced current generation as the concentration increased. According to the results of electrochemical analyses, the i-V graphs represent that the catalytic current induced by the primitive electron shuttles started at the onset potential of −0.27 V and continued increasing until +0.73 V. In the riboflavin-addition experiment, the catalytic current initiated at the same potential but rapid saturated beyond −0.07 V; this indicated that the addition of riboflavin affects mediator secretion by S. decolorationis NTOU1. It was also found that the current was eliminated after adding 48 mM N-acetyl-L-methionine (i.e., the cytochrome inhibitor) when using acetate as a substrate, indicating the importance of outer-membrane cytochrome.

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A metabolic-activity-detecting approach to life detection: Restoring a chemostat from stop-feeding using a rapid bioactivity assay

Cited by 8 publications

References 54 publications

Electrons selective uptake of a metal-reducing bacterium Shewanella oneidensis MR-1 from ferrocyanide

Electrons selective uptake of a metal-reducing bacterium Shewanella oneidensis MR-1 from ferrocyanide

Investigating the Extracellular-Electron-Transfer Mechanisms and Kinetics of Shewanella decolorationis NTOU1 Reducing Graphene Oxide via Lactate Metabolism

Chemical Characteristics of Electron Shuttles Affect Extracellular Electron Transfer: Shewanella decolorationis NTOU1 Simultaneously Exploiting Acetate and Mediators

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