Suchergebnisse

The reversible oxidation and reduction of Cytochrome c (Cyt c) is demonstrated with a closed bipolar electrochemical cell (CBPEC). Herein, a 4-electrode configuration was studied with the opposite poles of the bipolar electrode resting in separate aqueous and organic electrolyte solutions, respectively. Using biocompatible indium tin oxide (ITO) slides as the bipolar electrode poles, we investigated the influence of the redox potential of the reductant (decamethyferrocene or dimethylferrocene) in a trifluorotoluene organic phase on the observed voltammetry. Reversible electron transfer was only observed between Cyt c and decamethylferrocene. Use of the weaker dimethylferrocene as the reductant required a larger external bias of the driving electrodes to initiate the electron transfer reaction between the two poles of the bipolar electrode. Consequently, the surface of the ITO slide at the aqueous pole experienced a significant negative cathodic potential and underwent irreversible reduction. The biphasic setup using the 4-electrode CBPEC provides insights into electron transfer processes at an interface between two immiscible electrolyte solutions (ITIES), highlighting the strong probability of observing interfacial electron transfer between decamethylferrocene (but not dimethylferrocene) and Cyt c within the short ~ 1 V polarisable potential window available at an ITIES. ; A. G.-Q. acknowledges funding received from an Irish Research Council Government of Ireland Postdoctoral Fellowship Award (grant number GOIPD/2018/252). G. H. is grateful to the French Programme Investissement d'Avenir (PIA) "Lorraine Université d'Excellence" (Reference No. ANR-15-IDEX-04-LUE). for the partial financial support of this work. The authors are grateful to the support of the Irish Research Council and Campus France for travel support between the French and Irish groups through their joint ULYSSES programme.

This study aims at elucidating the metabolic pathways involved in the production of volatile fatty acids from CO2 and electricity. Two bioelectrochemical systems (BES) were fed with pure CO2 (cells A and B). The cathode potential was first poised at −574 mV vs. standard hydrogen electrode (SHE) and then at −756 mV vs. SHE in order to ensure the required reducing power. Despite applying similar operation conditions to both BES, they responded differently. A mixture of organic compounds (1.87 mM acetic acid, 2.30 mM formic acid, 0.43 mM propionic acid, 0.15 mM butyric acid, 0.55 mM valeric acid, and 0.62 mM ethanol) was produced in cell A while mainly 1.82 mM acetic acid and 0.23 mM propionic acid were produced in cell B. The microbial community analysis performed by 16S rRNA gene pyrosequencing showed a predominance of Clostridium sp. and Serratia sp. in cell A whereas Burkholderia sp. and Xanthobacter sp. predominated in cell B. The coexistence of three metabolic pathways involved in carbon fixation was predicted. Calvin cycle was predicted in both cells during the whole experiment while Wood-Ljungdahl and Arnon-Buchanan pathways predominated in the period with higher coulombic efficiency. Metabolic pathways which transform organic acids into anabolic intermediaries were also predicted, indicating the occurrence of complex trophic interactions. These results further complicate the understanding of these mixed culture microbial processes but also expand the expectation of compounds that could potentially be produced with this technology ; This research was financially supported by the Spanish Government (CTQ 2014-53718-R) and the National Agency of Research and Innovation of Uruguay (ANII; FSE6437 and FSE102488). JW was funded by the ANII-PhD grant (SNB). LEQUIA has been recognized as a consolidated research group by the Catalan Government under the code 2014-SGR-1168

Hydrogen-oxidizing bacteria (HOBs) are prime candidates for the sustainable production of microbial protein because of their high nutritional value and simple metabolic requirements, which could allow a simple resource recycling of NH4+ and CO2 into a valuable product. The modality of hydrogen production/supply to HOBs represents a challenge. In this work, bioelectrochemical hydrogen and oxygen productions were coupled with HOBs cultivation in the same reactor. Using this approach, the protein content was 59 ± 8% with Hydrogenophaga and Xanthobacter as the most abundant HOBs. Biomass concentration was found to be dependent of the current density with bulk liquid biomass increasing between 101 and 124 mg TSS·L−1 for an increase of 0.1 mA·cm−2. Electrodes directly immersed in the bioreactor promoted biofilm formation on the electrode surface, which could become an attractive alternative for biomass harvesting. The results of this work establish a novel proof-of-concept for bio-electro production of microbial protein ; This research was carried out in the project "RITA – urban cycle ResIlient To pAndemics) funded by AGAUR (ref. 2020PANDE00176). The authors acknowledge the technical support of Ms. Sandra Cano and Mr. Juan José Murga. S.P. is a Serra Hunter Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Academia award. LEQUIA (2017-SGR-1552) and Ecoaqua (2017-SGR-548) have been recognized as consolidated research groups by the Catalan Government

AbstractA microbial electrolysis cell was established to explore the degradation characteristics of characteristic pollutants in wastewater for parabromoaniline (P‐BrA). Their effects on P‐BrA reduction and degradation were investigated through factors such as impressed voltage and cosubstrate type. The P‐BrA residue and degradation in wastewater were analysed quantitatively through analytical testing methods, such as ultraviolet–visible, cyclic voltammetry, high‐performance liquid chromatograph, and scanning electron microscopy. The results showed that under the cathode potential of 0.5 V, electrons and electroactive microorganisms generate coupling action to accelerate the degradation of P‐BrA, reaching 94.94%. Moreover, the addition of carbon source organisms, such as glucose and sodium acetate, can facilitate the degradation of P‐BrA in the cathode chamber on the precondition that the electroactive anaerobic microbial C/N ratio was satisfied, both reaching over 90%. In addition, the microbial community diversity and richness of bioelectrochemistry system were enhanced after bioaugmentation. The increase in the Anacrolincalcs, Betaproteobacteriales, and Micrococcales also played an important role in the granulation of bioelectrochemistry system and the removal of characteristic pollutants.

Decarbonisation of the economy has become a priority at the global level, and the resulting legislative pressure is pushing the chemical and energy industries away from fossil fuels. Microbial electrosynthesis (MES) has emerged as a promising technology to promote this transition, which will further benefit from the decreasing cost of renewable energy. However, several technological challenges need to be addressed before the MES technology can reach its maturity. The aim of this review is to critically discuss the bottlenecks hampering the industrial adoption of MES, considering the whole production process (from the CO2 source to the marketable products), and indicate future directions. A flexible stack design, with flat or tubular MES modules and direct CO2 supply, is required for site-specific decentralised applications. The experience gained for scaling-up electrochemical cells (e.g. electrolysers) can serve as a guideline for realising pilot MES stacks to be technologically and economically evaluated in industrially relevant conditions. Maximising CO2 abatement rate by targeting high-rate production of acetate can promote adoption of MES technology in the short term. However, the development of a replicable and robust strategy for production and in-line extraction of higher-value products (e.g. caproic acid and hexanol) at the cathode, and meaningful exploitation of the currently overlooked anodic reactions, can further boost MES cost-effectiveness. Furthermore, the use of energy storage and smart electronics can alleviate the fluctuations of renewable energy supply. Despite the unresolved challenges, the flexible MES technology can be applied to decarbonise flue gas from different sources, to upgrade industrial and wastewater treatment plants, and to produce a wide array of green and sustainable chemicals. The combination of these benefits can support the industrial adoption of MES over competing technologies ; This work was performed on the framework of the Science Foundation Ireland (SFI) Pathfinder ...

Research on biosensors is growing in relevance, taking benefit from groundbreaking knowledge that allows for new biosensing strategies. Electrochemical biosensors can benefit from research on semiconducting materials for energy applications. This research seeks the optimization of the semiconductor-electrode interfaces including light-harvesting materials, among other improvements. Once that knowledge is acquired, it can be implemented with biological recognition elements, which are able to transfer a chemical signal to the photoelectrochemical system, yielding photo-biosensors. This has been a matter of research as it allows both a superior suppression of background electrochemical signals and the switching ON and OFF upon illumination. Effective electrode-semiconductor interfaces and their coupling with biorecognition units are reviewed in this work. ; European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 713366. G. Luna-López wishes to thank to "Comunidad de Madrid" and European Structural Funds for their financial support to FotoArt-CM project (S2018/NMT-4367). M. Pita thanks the Retos MCIU/AEI/FEDER, EU for funding project RTI2018-095090-B-I00.

Biogas upgrading is an expanding field dealing with the increase in methane content of the biogas to produce biomethane. Biomethane has a high calorific content and can be used as a vehicle fuel or directly injected into the gas grid. Bioelectrochemical systems (BES) could become an alternative for biogas upgrading, by which the yield of the process in terms of carbon utilisation could be increased. The simulated effluent from a water scrubbing-like unit was used to feed a BES. The BES was operated with the biocathode poised at −800 mV vs. SHE to drive the reduction of the CO2 fraction of the biogas into methane. The BES was operated in batch mode to characterise methane production and under continuous flow to demonstrate its long-term viability. The maximum methane production rate obtained during batch tests was 5.12 ± 0.16 mmol m−2 per day with a coulombic efficiency (CE) of 75.3 ± 5.2%. The production rate increased to 15.35 mmol m−2 per day (CE of 68.9 ± 0.8%) during the continuous operation. Microbial community analyses and cyclic voltammograms showed that the main mechanism for methane production in the biocathode was hydrogenotrophic methanogenesis by Methanobacterium sp., and that electromethanogenesis occurred to a minor extent. The presence of other microorganisms in the biocathode, such as Methylocystis sp. revealed the presence of side reactions, such as oxygen diffusion from the anode compartment, which decreased the efficiency of the BES. The results of the present work offer the first experimental report on the application of BES in the field of biogas upgrading processes ; This research was nancially supported by the Spanish Government (CTQ 2014-53718-R). P. B-V. and A. V-P. were supported by a project grant from the Catalan Government (2014 FIB1 00119 and 2014 FI-B 00093). LEQUIA has been recognised as consolidated research group by the Catalan Government with code 2014-SGR-1168. Authors acknowledge the collaboration of Lluis Baneras from the Group of Molecular Microbial Ecology (University of Girona), who helped with the microbial analyses

Biogas upgrading is an expanding field dealing with the increase in methane content of the biogas to produce biomethane. Biomethane has a high calorific content and can be used as a vehicle fuel or directly injected into the gas grid. Bioelectrochemical systems (BES) could become an alternative for biogas upgrading, by which the yield of the process in terms of carbon utilisation could be increased. The simulated effluent from a water scrubbing-like unit was used to feed a BES. The BES was operated with the biocathode poised at −800 mV vs. SHE to drive the reduction of the CO2 fraction of the biogas into methane. The BES was operated in batch mode to characterise methane production and under continuous flow to demonstrate its long-term viability. The maximum methane production rate obtained during batch tests was 5.12 ± 0.16 mmol m−2 per day with a coulombic efficiency (CE) of 75.3 ± 5.2%. The production rate increased to 15.35 mmol m−2 per day (CE of 68.9 ± 0.8%) during the continuous operation. Microbial community analyses and cyclic voltammograms showed that the main mechanism for methane production in the biocathode was hydrogenotrophic methanogenesis by Methanobacterium sp., and that electromethanogenesis occurred to a minor extent. The presence of other microorganisms in the biocathode, such as Methylocystis sp. revealed the presence of side reactions, such as oxygen diffusion from the anode compartment, which decreased the efficiency of the BES. The results of the present work offer the first experimental report on the application of BES in the field of biogas upgrading processes ; This research was nancially supported by the Spanish Government (CTQ 2014-53718-R). P. B-V. and A. V-P. were supported by a project grant from the Catalan Government (2014 FIB1 00119 and 2014 FI-B 00093). LEQUIA has been recognised as consolidated research group by the Catalan Government with code 2014-SGR-1168. Authors acknowledge the collaboration of Lluis Baneras from the Group of Molecular Microbial Ecology (University of Girona), who helped with the microbial analyses

Biogas upgrading is an expanding field dealing with the increase in methane content of the biogas to produce biomethane. Biomethane has a high calorific content and can be used as a vehicle fuel or directly injected into the gas grid. Bioelectrochemical systems (BES) could become an alternative for biogas upgrading, by which the yield of the process in terms of carbon utilisation could be increased. The simulated effluent from a water scrubbing-like unit was used to feed a BES. The BES was operated with the biocathode poised at −800 mV vs. SHE to drive the reduction of the CO2 fraction of the biogas into methane. The BES was operated in batch mode to characterise methane production and under continuous flow to demonstrate its long-term viability. The maximum methane production rate obtained during batch tests was 5.12 ± 0.16 mmol m−2 per day with a coulombic efficiency (CE) of 75.3 ± 5.2%. The production rate increased to 15.35 mmol m−2 per day (CE of 68.9 ± 0.8%) during the continuous operation. Microbial community analyses and cyclic voltammograms showed that the main mechanism for methane production in the biocathode was hydrogenotrophic methanogenesis by Methanobacterium sp., and that electromethanogenesis occurred to a minor extent. The presence of other microorganisms in the biocathode, such as Methylocystis sp. revealed the presence of side reactions, such as oxygen diffusion from the anode compartment, which decreased the efficiency of the BES. The results of the present work offer the first experimental report on the application of BES in the field of biogas upgrading processes ; This research was nancially supported by the Spanish Government (CTQ 2014-53718-R). P. B-V. and A. V-P. were supported by a project grant from the Catalan Government (2014 FIB1 00119 and 2014 FI-B 00093). LEQUIA has been recognised as consolidated research group by the Catalan Government with code 2014-SGR-1168. Authors acknowledge the collaboration of Lluis Baneras from the Group of Molecular Microbial Ecology (University of ...

New strategies in inoculation and operation of bioelectrochemical systems were used to advance in the steering of bio-electro carbon dioxide (CO2) recycling towards chemical compounds. First, the preparation of microbe coated biocathodes ex-situ with putative electroactive species with CO2 as sole carbon source was assayed. Second, CO2 feeding strategies for the operation of BES systems were explored to ensure enough reducing power during batch mode operation. The impact on the proposed changes on the product portfolio and production yields was assessed. The initial enrichment of a putative electroactive community on bare electrode surfaces was proven to be successful and led to a shortening of the start-up period of the system from days to hours. Moreover, the establishment of a new feeding procedure to favor the presence of elevated reducing power availability for cells triggered the production of longer carbon chain carboxylates (max. 0.99 gbutyrate m-2electrode d-1) and alcohols (max. 0.83 gethanol m-2electrode d-1) at early stages of experiment. This work complements the recent knowledge on the control of bioelectrochemical processes by the establishment of strategies to obtain target added-value compounds from CO2 ; R.B-G. was supported by a grant from the Spanish Ministry of Economy and Competitiveness (MINECO) (FPI grant BES-2015-074229 within the research project CTQ2014-53718R). E. P.-V. is grateful for the Research Training grant from the University of Girona (IFUdG2018/52). S.P. is a Serra Hunter Fellow (UdG-AG-575) and acknowledges the funding from the ICREA Academia award. This research was funded by the Agency for Business Competitiveness of the Government of Catalonia (ACCIÓ; COMRDI16-1-0061) and the Spanish Ministry of Science (RTI2018-098360-B-I00). LEQUIA and EcoAqua groups have been recognized as consolidated research groups by the Catalan Government (2017SGR-1552 and 2017SGR-548)

The present work assessed the alliance of microbial electrochemical technologies (METs) and fermentation in a two-step process for the electro-bioconversion of carbon dioxide (CO2) into elongated chemical building blocks. The electro bio-reduction of CO2 into acetic acid and ethanol (EtOH:HAc) at a 1-to-1 ratio is linked to a subsequent elongation step to produce C4 and C6 compounds. Key operational conditions of each step were assessed. Key parameters considered in the first step were pH, and both hydrogen and CO2 partial pressures. Concerning the second stage, selected parameters were pH, ethanol to acetate ratio, and hydrogen availability. The aim was to steer each stage's performance and to obtain higher value products. Reached EtOH:HAc proportion was over 1:1 when fed with CO2, with H2 availability and at pH around 5.3. Formed product reinforced the follow-up chain elongation processes. The fermentation step got up to C6 compounds at pH 7.0, when fed with CO2 and H2. Outcomes demonstrated that pH was a crucial factor in the overall process. The overall process carbon conversion efficiency was 38% being the CO2 transformation the limiting step. 1 kg of CO2 fed in the system resulted in the production of 0.38 kg of elongated acids (C4-C6). In other words, 1 m3 of CO2 (normal conditions) captured resulted firstly in the production of 0.90 kg CC2 and then, 0.75 kg CC4-C6 are finally acquired. The presented results pave the ground for improving the selectivity during the production of reduced commodity chemicals from CO2 and electricity ; The authors acknowledge funding from the Agency for Business Competitiveness of the Government of Catalonia (ACCIO; COMRDI16-1-0061) and the Spanish Ministry of Science (RTI2018-098360-B-I00). M.R-C. is grateful for the support of the Catalan Government (2021 FI_B 00499). R.B-G. is grateful for the FPI Grant BES-2015–074229 in the framework of the project CTQ2014-53718-R given by the Spanish Ministry of Economy and Competitiveness (MINECO). S.P. is a Serra Hunter Fellow ...

Electromethanogenesis is the bioreduction of carbon dioxide (CO2) to methane (CH4) utilizing an electrode as electron donor. Some studies have reported the active participation of Methanobacterium sp. in electron capturing, although no conclusive results are available. In this study, we aimed at determining short-time changes in the expression levels of [NiFe]-hydrogenases (Eha, Ehb and Mvh), heterodisulfide reductase (Hdr), coenzyme F420-reducing [NiFe]-hydrogenase (Frh), and hydrogenase maturation protein (HypD), according to the electron flow in independently connected carbon cloth cathodes poised at– 800 mV vs. standard hydrogen electrode (SHE). Amplicon massive sequencing of cathode biofilm confirmed the presence of an enriched Methanobacterium sp. population (>70% of sequence reads), which remained in an active state (78% of cDNA reads), tagging this archaeon as the main methane producer in the system. Quantitative RT-PCR determinations of ehaB, ehbL, mvhA, hdrA, frhA, and hypD genes resulted in only slight (up to 1.5 fold) changes for four out of six genes analyzed when cells were exposed to open (disconnected) or closed (connected) electric circuit events. The presented results suggested that suspected mechanisms for electron capturing were not regulated at the transcriptional level in Methanobacterium sp. for short time exposures of the cells to connected-disconnected circuits. Additional tests are needed in order to confirm proteins that participate in electron capturing in Methanobacterium sp ; This work was funded by Spanish Government (MINECO, CTQ2014-53718-R) and the Universitat de Girona (MPCUdG2016/139 and MCPUdG2016/121). Sebastià Puig is a Serra Hunter Fellow (UdG-AG-575). Ramiro Blasco-Gómez is grateful for the Research Personnel Training (FPI) grant (BES-2015-074229). Elisabet Perona-Vico received a Research Training grant from the University of Girona (IFUdG2018/52). LEQUiA and IEA have been recognized as consolidated research groups by the Generalitat de Catalunya (2017SGR-1552, and ...

The use of biocathodes in bioelectrochemical systems (BES) for the removal of nitrate in wastewater has become a vital field of research. However, the elucidation of the underlying extracellular electron transfer (EET) fundamentals of denitrifying biocathodes is still lacking, but required for a deeper BES understanding and engineering. This study reports for the first time on the thermodynamics of microbial cathodes for nitrate and nitrite reductions using microbial microcosms isolated from a running denitrifying BES. Cyclic voltammetry showed that nitrate and nitrite reduction proceed at - 0.30 V, and - 0.70 V vs. Ag/AgCl, respectively, by surface associated EET sites. The biocathodes were predominantly covered by Thiobacillus sp. contributing with a nitrate reductase (narG) to the major function of the microcosms. In conclusion, the EET characteristics of denitrifying biocathodes are demonstrated for the first time ; The authors acknowledge the scientific assistance of Prof. M.D. Balaguer. F.H. acknowledges support by the BMBF (Research Award "Next generation biotechnological processes-Biotechnology 2020+") and the Helmholtz Association (Young Investigators Group). This work was supported by the Helmholtz Association within the Research Programme Terrestrial Environment and by the Spanish Government (CTQ2011-23632). N.P. was supported by the Catalan Government (2012FI-B00941) and the University of Girona (MOB2014-ref22)

The use of biocathodes in bioelectrochemical systems (BES) for the removal of nitrate in wastewater has become a vital field of research. However, the elucidation of the underlying extracellular electron transfer (EET) fundamentals of denitrifying biocathodes is still lacking, but required for a deeper BES understanding and engineering. This study reports for the first time on the thermodynamics of microbial cathodes for nitrate and nitrite reductions using microbial microcosms isolated from a running denitrifying BES. Cyclic voltammetry showed that nitrate and nitrite reduction proceed at - 0.30 V, and - 0.70 V vs. Ag/AgCl, respectively, by surface associated EET sites. The biocathodes were predominantly covered by Thiobacillus sp. contributing with a nitrate reductase (narG) to the major function of the microcosms. In conclusion, the EET characteristics of denitrifying biocathodes are demonstrated for the first time ; The authors acknowledge the scientific assistance of Prof. M.D. Balaguer. F.H. acknowledges support by the BMBF (Research Award "Next generation biotechnological processes-Biotechnology 2020+") and the Helmholtz Association (Young Investigators Group). This work was supported by the Helmholtz Association within the Research Programme Terrestrial Environment and by the Spanish Government (CTQ2011-23632). N.P. was supported by the Catalan Government (2012FI-B00941) and the University of Girona (MOB2014-ref22)