Research article from the ERA Chair and collaborators from Chalmers University of Technology published in Biotechnology Resource Reports investigated the effects of culture conditions on the gas-fermenting acetogen Clostridium ljungdahlii in a microbial electrosynthesis system. The bacterium is electroactive meaning it can fix CO2using electrons sourced from electricity (through H2) and the work detected H2-mediated extracellular electron transfer. Optimal conditions for highest productivity and reproducibility of the bioelectrochemical system were determined. The work contributes towards the development of more efficient bioprocesses using Clostridium ljungdahlii as a biocatalyst.