Carboxylic acids production and electrosynthetic microbial community evolution under different CO2 feeding regimens

Microbial electrosynthesis (MES) is a potential technology for CO2 recycling, but insufficient information available on the microbial interactions underpinning electrochemically-assisted reactions. In this study, MES reactor was operated 225 days alternately with bicarbonate or as carbon source, under batch continuous feeding regimens, to evaluate response of communities, and their productivity, dynamic operating conditions. A stable acetic acid production rate 9.68 g m-2 d-1, coulombic efficiency up 40%, achieved sparging, higher than rates obtained (0.94 d-1) fed-batch conditions (2.54 d-1). However, highest butyric (0.39 intermittent sparging. The community analyses focused differential amplicon sequence variants (ASVs), allowing detection ASVs significantly different across consecutive samples. This analysis, combined co-occurence network cyclic voltammetry, indicated that hydrogen-mediated acetogenesis carried out by Clostridium, Eubacterium Acetobacterium, whereas Oscillibacter Caproiciproducens were involved in production. cathodic spatially inhomogeneous, electrotrophs, such Sulfurospirillum Desulfovibrio, most prevalent near current collector. abundance positively correlated supporting syntrophic metabolism both organisms.