Suchergebnisse

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 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 ...

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)