An acetogenic microbiome previously enriched on graphite granule cathodes at potentials from -590 to -800 mV vs. SHE was used to inoculate the bioreactors (LaBelle et al., 2014 (link)). The cells were drawn from the cathode compartment of an active reactor and were concentrated using tangential flow filtration using a 0.2 μm polyethersulfone filter (Sartorius), spun at 5000 (RCF) for 10 min and re-suspended in fresh medium before transfer to the RVC cathode reactors. The culture, inoculum and reactor, were treated as an open, non-aseptic system.
The reactor was operated at 25°C with constant current supplied from a VMP3 Potentiostat (BioLogic) set in galvanostatic mode and the voltage monitored with EC Lab software. A galvanostatic operation of 8 A/Lcatholyte was chosen to overcome electron limitation to a biofilm immobilized on the cathode and promote fast colonization. Humidified 100% CO2 was passed through the catholyte headspace using Norprene tubing at an initially set rate of 25 mL/min. Filter sterilized medium was flowed into the base of the cathode compartment and exited just above the top of the RVC cathode at a rate of 250 mL/day (a dilution rate of 5 day-1) using a peristaltic pump and PharMed BPT tubing. Deionized water was added to ports made from syringe housing on the anolyte compartment daily to compensate for water oxidation and evaporation.
The reactor was operated at 25°C with constant current supplied from a VMP3 Potentiostat (BioLogic) set in galvanostatic mode and the voltage monitored with EC Lab software. A galvanostatic operation of 8 A/Lcatholyte was chosen to overcome electron limitation to a biofilm immobilized on the cathode and promote fast colonization. Humidified 100% CO2 was passed through the catholyte headspace using Norprene tubing at an initially set rate of 25 mL/min. Filter sterilized medium was flowed into the base of the cathode compartment and exited just above the top of the RVC cathode at a rate of 250 mL/day (a dilution rate of 5 day-1) using a peristaltic pump and PharMed BPT tubing. Deionized water was added to ports made from syringe housing on the anolyte compartment daily to compensate for water oxidation and evaporation.
Free full text: Click here
