Biofilm matrix and artificial mediator for efficient electron transport in CO2 microbial electrosynthesis

Microbial electrosynthesis (MES) has been highlighted as a means to valorize inorganic gaseous carbon, such CO2, into value-added chemicals using electricity the reducing power. Electrode-based electron transfer delivers respiratory electrons live-cell biocatalyst through biofilm matrix or via shuttle molecules. The addition of artificial mediators, neutral red (NR) and 2-hydroxy-1,4-naphthoquinone (HNQ), increased acetate synthesis significantly, suggesting that these mediators improve transport capability between suspended cells electrode. Regular media replacement also improves MES by adapting mediator-utilizing species in reactor. without mediator initially produced at reasonable rate (5.1 ± 0.2 mmol/l/day), but became negligible later stage. In contrast, with NR HNQ showed higher production (4.6 0.4 vs. 7.4 mmol/l/day, respectively) progressed. Confocal laser scanning microscopy 3D imaging consisted live dead cells, while composition was different mediator. community analysis next-generation sequencing (NGS) acetogenic Acetobacterium (in suspension) Sporomusa both suspension biofilm) were dominant during 96 days operation. planktonic interacted dynamically under conditions. This result provides realistic model biofilms MES. interaction biofilm-forming electrode shuttles could volumetric stabilize performance.