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Bioelectrochemistry. 2017 Feb;113:26-34. doi: 10.1016/j.bioelechem.2016.09.001. Epub 2016 Sep 4.

Long-term operation of microbial electrosynthesis cell reducing CO2 to multi-carbon chemicals with a mixed culture avoiding methanogenesis.

Author information

1
Separation & Conversion Technologies, Flemish Institute for Technological Research (VITO), Mol, Belgium; Sub-department of Environmental Technology, Wageningen University, Wageningen, The Netherlands.
2
Sub-department of Environmental Technology, Wageningen University, Wageningen, The Netherlands.
3
Separation & Conversion Technologies, Flemish Institute for Technological Research (VITO), Mol, Belgium.
4
Sub-department of Environmental Technology, Wageningen University, Wageningen, The Netherlands. Electronic address: david.strik@wur.nl.
5
Separation & Conversion Technologies, Flemish Institute for Technological Research (VITO), Mol, Belgium. Electronic address: deepak.pant@vito.be.

Abstract

In microbial electrosynthesis (MES), CO2 can be reduced preferably to multi-carbon chemicals by a biocathode-based process which uses electrochemically active bacteria as catalysts. A mixed anaerobic consortium from biological origin typically produces methane from CO2 reduction which circumvents production of multi-carbon compounds. This study aimed to develop a stable and robust CO2 reducing biocathode from a mixed culture inoculum avoiding the methane generation. An effective approach was demonstrated based on (i) an enrichment procedure involving inoculum pre-treatment and several culture transfers in H2:CO2 media, (ii) a transfer from heterotrophic to autotrophic growth and (iii) a sequential batch operation. Biomass growth and gradual acclimation to CO2 electro-reduction accomplished a maximum acetate production rate of 400mgLcatholyte-1d-1 at -1V (vs. Ag/AgCl). Methane was never detected in more than 300days of operation. Accumulation of acetate up to 7-10gL-1 was repeatedly attained by supplying (80:20) CO2:N2 mixture at -0.9 to -1V (vs. Ag/AgCl). In addition, ethanol and butyrate were also produced from CO2 reduction. Thus, a robust CO2 reducing biocathode can be developed from a mixed culture avoiding methane generation by adopting the specific culture enrichment and operation procedures without the direct addition of chemical inhibitor.

KEYWORDS:

Autotrophic bioproduction; Biocathode; CO(2) reduction; Microbial electrosynthesis; Wood-Ljungdahl pathway

[Indexed for MEDLINE]

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