Bioelectrochemical reduction of carbon dioxide by pure culture at the cathode

Microbial electrosynthesis (MES) is an innovative approach in which microbes use electricity toreduce carbon dioxide and produce chemical commodities. This process relies on the ability of electroautotrophic microbes to accept electron from an electrode. The concept of MES has already been demonstrated with pure cultures of acetogenic bacteria such as Sporomusa ovate DSM-2662 and Clostridium ljungdahlii. Until now, electron transfer rates from the cathode to the bestelectroautotroph, S. ovata, are still orders of magnitude lower than what is observed in bioanodicprocesses with electrigenic bacteria. Hence, we are screening other pure cultures for better MES activities. These bacterial species were pre-selected based on several criteria such as their presence in enrichments of environmental samples in MES systems, their capacity to fix CO2, their incapacity to sporulate, and their ability to form robust biofilms. In preliminary results, 171.9mM ofacetate per day per m2 was produced by a previously uncharacterized strain of Sporomusa ovata which is approximatively 1.4 times better than S. ovata DSM-26621. This demonstrates that better electroautotrophic bacteria can still be uncovered leading to more productive MES process.