Iron reduction by the cyanobacterium Synechocystis sp. PCC 6803

Thorne, Rebecca Jayne; Schneider, K.J.; Hu, Huaining; Cameron, Petra J.

doi:10.1016/j.bioelechem.2015.05.015

Cited by 9 publications

(8 citation statements)

References 33 publications

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“…Culturing conditions were similar to those encountered in BPV experiments, which typically consist of a light/dark cycle with temperatures up to 30 C, alkaline pH and in aerated conditions. It has been reported that growth rates of PCC7942 do not increase above the 100-120 mmol m À2 s À1 , 51,52 therefore experiments were conducted under a light intensity of 90 mmol m À2 s…”

Section: Pcc7942 Exoelectrogenesis Under Iron Limited Growthmentioning

confidence: 99%

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Tapping into cyanobacteria electron transfer for higher exoelectrogenic activity by imposing iron limited growth

et al. 2018

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The exoelectrogenic capacity of the cyanobacterium Synechococcus elongatus PCC7942 was studied in iron limited growth in order to establish conditions favouring extracellular electron transfer in cyanobacteria for photo-bioelectricity generation. Investigation into extracellular reduction of ferricyanide by Synechococcus elongatus PCC7942 demonstrated enhanced capability for the iron limited conditions in comparison to the iron sufficient conditions. Furtheremore, the significance of pH showed that higher rates of ferricyanide reduction occurred at pH 7, with a 2.7-fold increase with respect to pH 9.5 for iron sufficient cultures and 24-fold increase for iron limited cultures. The strategy presented induced exoelectrogenesis driven mainly by photosynthesis and an estimated redirection of the 28% of electrons from photosynthetic activity was achieved by the iron limited conditions. In addition, ferricyanide reduction in the dark by iron limited cultures also presented a significant improvement, with a 6-fold increase in comparison to iron sufficient cultures. Synechococcus elongatus PCC7942 ferricyanide reduction rates are unprecedented for cyanobacteria and they are comparable to those of microalgae. The redox activity of biofilms directly on ITO-coated glass, in the absence of any artificial mediator, was also enhanced under the iron limited conditions, implying that iron limitation increased exoelectrogenesis at the outer membrane level. Cyclic voltammetry of Synechococcus elongatus PCC7942 biofilms on ITO-coated glass showed a midpoint potential around 0.22 V vs. Ag/ AgCl and iron limited biofilms had the capability to sustain currents in a saturated-like fashion. The present work proposes an iron related exoelectrogenic capacity of Synechococcus elongatus PCC7942 and sets a starting point for the study of this strain in order to improve photo-bioelectricity and darkbioelectricity generation by cyanobacteria, including more sustainable mediatorless systems.

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Section: Pcc7942 Exoelectrogenesis Under Iron Limited Growthmentioning

confidence: 99%

“…In the case of cyanobacteria, some authors 10,30 have suggested that exoelectrogenesis may be due to a reductive iron uptake mechanism as well. Although, proteins with the conserved ferric reductase domain have not been annotated for cyanobacteria.…”

Section: 29mentioning

confidence: 99%

Tapping into cyanobacteria electron transfer for higher exoelectrogenic activity by imposing iron limited growth

et al. 2018

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“…In addition, the reduction reaction is mass transfer limited when there is an excess of cells for a given concentration of ferricyanide (see Ferricyanide assay in Methods for a review of reported mass transfer-limiting combinations of cell and ferricyanide concentrations for two species of cyanobacteria and algae) [ 28 ]. In mass transfer-controlled heterogenous catalytic surface reactions, the reaction rate is equivalent to the external mass transfer rate to the catalytic surface [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis of the effects of morphological changes on extracellular electron transfer rates in cyanobacteria

Okedi

Fisher

Yunus

2020

Biotechnol Biofuels

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Background: Understanding the extracellular electron transport pathways in cyanobacteria is a major factor towards developing biophotovoltaics. Stressing cyanobacteria cells environmentally and then probing changes in physiology or metabolism following a significant change in electron transfer rates is a common approach for investigating the electron path from cell to electrode. However, such studies have not explored how the cells' concurrent morphological adaptations to the applied stresses affect electron transfer rates. In this paper, we establish a ratio to quantify this effect in mediated systems and apply it to Synechococcus elongatus sp. PCC7942 cells grown under different nutritional regimes. Results: The results provide evidence that wider and longer cells with larger surface areas have faster mediated electron transfer rates. For rod-shaped cells, increase in cell area as a result of cell elongation more than compensates for the associated decline in mass transfer coefficients, resulting in faster electron transfer. In addition, the results demonstrate that the extent to which morphological adaptations account for the changes in electron transfer rates changes over the bacterial growth cycle, such that investigations probing physiological and metabolic changes are meaningful only at certain time periods. Conclusion: A simple ratio for quantitatively evaluating the effects of cell morphology adaptations on electron transfer rates has been defined. Furthermore, the study points to engineering cell shape, either via environmental conditioning or genetic engineering, as a potential strategy for improving the performance of biophotovoltaic devices.

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“…The use of phototrophs in p-MFCs, therefore, allows for use of simpler set-ups with lower energy consumption. p-MFCs continue to produce power in the dark and it has been shown by several research groups that the photosynthetic microorganisms are able to donate electrons to the anode both while they are photosynthesizing and while they are respiring in the dark [3,10,11].…”

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confidence: 99%

“…Electrons can be transferred from electrogenic cells (organisms that can produce a current by donating electrons to acceptors in the environment) to the anode by a variety of mechanisms [12,13]. In the first mechanism, a redox mediator shuttles the electrons from the cells to the anode [10,14]. Redox mediators can either be naturally occurring (small molecules secreted by the organisms themselves) or artificial (added to the electrolyte) [5,15,16].…”

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An investigation of anode and cathode materials in photomicrobial fuel cells

Schneider

Thorne

Cameron

2016

Phil. Trans. R. Soc. A.

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Photomicrobial fuel cells (p-MFCs) are devices that use photosynthetic organisms (such as cyanobacteria or algae) to turn light energy into electrical energy. In a p-MFC, the anode accepts electrons from microorganisms that are either growing directly on the anode surface (biofilm) or are free floating in solution (planktonic). The nature of both the anode and cathode material is critical for device efficiency. An ideal anode is biocompatible and facilitates direct electron transfer from the microorganisms, with no need for an electron mediator. For a p-MFC, there is the additional requirement that the anode should not prevent light from perfusing through the photosynthetic cells. The cathode should facilitate the rapid reaction of protons and oxygen to form water so as not to rate limit the device. In this paper, we first review the range of anode and cathode materials currently used in p-MFCs. We then present our own data comparing cathode materials in a p-MFC and our first results using porous ceramic anodes in a mediator-free p-MFC.

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Iron reduction by the cyanobacterium Synechocystis sp. PCC 6803

Cited by 9 publications

References 33 publications

Tapping into cyanobacteria electron transfer for higher exoelectrogenic activity by imposing iron limited growth

Tapping into cyanobacteria electron transfer for higher exoelectrogenic activity by imposing iron limited growth

Quantitative analysis of the effects of morphological changes on extracellular electron transfer rates in cyanobacteria

An investigation of anode and cathode materials in photomicrobial fuel cells

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