Mixed-culture biocathodes for acetate production from CO2 reduction in the microbial electrosynthesis: Impact of temperature

The temperature effect on bioelectrochemical reduction of CO2 to acetate with a mixed-culture biocathode in the microbial electrosynthesis was explored. The results showed that maximum acetate amount of 525.84 ± 1.55 mg L−1 and fastest acetate formation of 49.21 ± 0.49 mg L−1 d−1 were obtained under mesophilic conditions. Electron recovery efficiency for CO2 reduction to acetate ranged from 14.50 ± 2.20% to 64.86 ± 2.20%, due to propionate, butyrate and H2 generation. Mesophilic conditions were demonstrated to be more favorable for biofilm formation on the cathode, resulting in a stable and dense biofilm. At phylum level, the relative abundance of Bacteroidetes phylum in the biofilm remarkably increased under mesophilic conditions, compared with that at psychrophilic and thermophilic conditions. At genus level, the Clostridium, Treponema, Acidithiobacillus, Acetobacterium and Acetoanaerobium were found to be dominated genera in the biofilm under mesophilic conditions, while genera diversity decreased under psychrophilic and thermophilic conditions. [Display omitted] •Temperature impact on acetate production with a mixed-culture biocathode was evaluated.•Acetate production with a mixed-culture biocathode was best at mesophilic condition.•Stable and dense biofilm was formed on the cathode under mesophilic conditions.•Higher microbial diversity of bicathodes was observed under mesophilic conditions.•Mesophilic condition was more favorable for the growth of acetogens on the cathode.