title: Selective Enrichment Establishes a Stable Performing Community for Microbial Electrosynthesis of Acetate from CO₂.
abstract: The advent of renewable energy conversion systems exacerbates the existing issue of intermittent excess power. Microbial electrosynthesis can use this power to capture CO2 and produce multicarbon compounds as a form of energy storage. As catalysts, microbial populations can be used, provided side reactions such as methanogenesis are avoided. Here a simple but effective approach is presented based on enrichment of a robust microbial community via several culture transfers with H2:CO2 conditions. This culture produced acetate at a concentration of 1.29 ± 0.15 g L(-1) (maximum up to 1.5 g L(-1); 25 mM) from CO2 at a fixed current of -5 Am(-2) in fed-batch bioelectrochemical reactors at high N2:CO2 flow rates. Continuous supply of reducing equivalents enabled acetate production at a rate of 19 ± 2 gm(-2)d(-1) (projected cathode area) in several independent experiments. This is a considerably high rate compared with other unmodified carbon-based cathodes. 58 ± 5% of the electrons was recovered in acetate, whereas 30 ± 10% of the electrons was recovered in H2 as a secondary product. The bioproduction was most likely H2 based; however, electrochemical, confocal microscopy, and community analyses of the cathodes suggested the possible involvement of the cathodic biofilm. Together, the enrichment approach and galvanostatic operation enabled instant start-up of the electrosynthesis process and reproducible acetate production profiles.
authors.affiliation: †Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Sunil A
authors.initials: SA
authors.lastname: Patil
authors.affiliation: †Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Jan B A
authors.initials: JB
authors.lastname: Arends
authors.forename: Inka
authors.initials: I
authors.lastname: Vanwonterghem
authors.affiliation: †Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Jarne
authors.initials: J
authors.lastname: van Meerbergen
authors.affiliation: †Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Kun
authors.initials: K
authors.lastname: Guo
authors.forename: Gene W
authors.initials: GW
authors.lastname: Tyson
authors.affiliation: †Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Korneel
authors.initials: K
authors.lastname: Rabaey
mesh_terms: D000085:Acetates / Q000378:metabolism*; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D001674:Bioelectric Energy Sources; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D015203:Reproducibility of Results
chemical_list: D000085:Acetates; D002245:Carbon Dioxide; D008697:Methane