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Item type:Publication, Access status: without files , Systematic investigation of anode materials for microbial fuel cells with the model organism G. sulfurreducensDifferent carbon and metal-based anode materials for microbial fuel cells were systematically investigated with a pure culture of the model organism G. sulfurreducens. The highest limiting current density of 756 ± 15 μA cm−2 at −0.253 ± 0.037 V vs. SCE was achieved with graphite foil using a step-wise galvanostatic technique. But also the application of completely different anode materials such as activated carbon cloth, stainless steel and graphite felt led to similar high limiting current densities, suggesting that G. sulfurreducens is able to use a large range of substantially different anode materials as external electron acceptor. Additionally, we could show that a step-wise galvanostatic technique to record polarization curves yields similar current densities as potentiostatic control at −0.400 V vs. SCE with the investigated carbon-based materials. In case of stainless steel these techniques yield slightly different results, presumably due to an effect related to the material's surface properties.Publicationtype: Journal Article24 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Unbalanced fermentation of glycerol in Escherichia coli via heterologous production of an electron transport chain and electrode interaction in microbial electrochemical cells(Elsevier, 2015-03-06); ; ; ; Microbial electrochemical cells are an emerging technology for achieving unbalanced fermentations. However, organisms that can serve as potential biocatalysts for this application are limited by their narrow substrate spectrum. This study describes the reprogramming of Escherichia coli for the efficient use of anodes as electron acceptors. Electron transfer into the periplasm was accelerated by 183% via heterologous expression of the c-type cytochromes CymA, MtrA and STC from Shewanella oneidensis. STC was identified as a target for heterologous expression via a two-stage screening approach. First, mass spectroscopic analysis revealed natively expressed cytochromes in S. oneidensis. Thereafter, the corresponding genes were cloned and expressed in E. coli to quantify periplasmic electron transfer activity using methylene blue. This redox dye was further used to expand electron transfer to carbon electrode surfaces. The results demonstrate that E. coli can be reprogrammed from glycerol fermentation to respiration upon production of the new electron transport chain.Publicationtype: Journal ArticleScopus© Citations 95 15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , How does the choice of anode material influence electrical performance? A comparison of two microbial fuel cell model organismsThe influence of the anode material on the electrical performance of the two microbial fuel cell model organisms Geobacter sulfurreducens and Shewanella oneidensis is investigated. High-surface-area activated carbon and low-surface-area graphite felt are compared in terms of polarization curves under quasi-steady-state conditions. Unexpectedly, G. sulfurreducens exhibits similar current densities up to 700μAcm-2 independent of the anode material. This is ~50% higher than steady-state values reported previously. The negligible influence of electrode material on the electrical performance of G. sulfurreducens is attributed to the fact that it performs only direct electron transfer, but forms thick biofilms. In contrast, S. oneidensis, relying mainly on mediated electron transfer, apparently makes better use of high-surface-area activated carbon and achieves higher current densities compared to graphite felt. This underlines the importance of tailoring anode materials according to the used organisms.Publicationtype: Journal Article27 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Systematic screening of carbon-based anode materials for microbial fuel cells with Shewanella oneidensis MR-1We present a systematic screening of carbon-based anode materials for microbial fuel cells with Shewanella oneidensis MR-1. Under anoxic conditions nanoporous activated carbon cloth is a superior anode material in terms of current density normalized to the projected anode area and anode volume (24.0±0.3μAcm-2 and 482±7μAcm-3 at -0.2 vs. SCE, respectively). The good performance can be attributed to the high specific surface area of the material, which is available for mediated electron transfer through self-secreted flavins. Under aerated conditions no influence of the specific surface area is observed, which we attribute to a shift from primary indirect electron transfer by mediators to direct electron transfer via adherent cells. Furthermore, we show that an aerated initial growth phase enhances the current density under subsequent anoxic conditions fivefold when compared to a similar experiment that was conducted under permanently anoxic conditions.Publicationtype: Journal ArticleScopus© Citations 63 16