Performance of different Sporomusa species for the microbial electrosynthesis of acetate from carbon dioxide

Abstract

Sporomusa ovata DSM-2662 produces high rate of acetate during microbial electrosynthesis (MES) by reducing CO₂ with electrons coming from a cathode. Here, we investigated other Sporomusa for MES with cathode potential set at -690mVvsSHE to establish if this capacity is conserved among this genus and to identify more performant strains. S. ovata DSM-2663 produced acetate 1.8-fold faster than S. ovata DSM-2662. On the contrary, S. ovata DSM-3300 was 2.7-fold slower whereas Sporomusa aerivorans had no MES activity. These results indicate that MES performance varies among Sporomusa. During MES, electron transfer from cathode to microbes often occurs via H₂. To establish if efficient coupling between H₂ oxidation and CO₂ reduction may explain why specific acetogens are more productive MES catalysts, the metabolisms of the investigated Sporomusa were characterized under H₂:CO₂. Results suggest that other phenotypic traits besides the capacity to oxidize H₂ efficiently are involved.

Keywords: Acetate; H(2) oxidation; Microbial catalyst; Microbial electrosynthesis; Sporomusa.