Acetate production and electron utilization facilitated by sulfate-reducing bacteria in a microbial electrosynthesis system

The aim of this study is to investigate the effect of sulfate-reducing bacteria on performance of a mixed culture microbial electrosynthesis system (MES). The two-chamber MESs were operated under different cathode potentials (-0.5, -0.6, -0.7, and -0.8 V) with or without addition of 6 mM sulfate. At -0.7 V, acetate production and electrons harvesting in the MES with the sulfate addition were 31.81 mM and 5152 C, respectively, which improved by 2.7 and 2.4 times compared to that without sulfate. With sulfate, the biomass, proportion of live cells, and electrochemical activity of cathode biofilm were enhanced at all the potentials. At -0.7 V, the relative abundance of Acetobacterium and Desulfovibrionaceae was 14.2% and 36.7% with sulfate, respectively, compared to 17.4% and 7.3% without sulfate. At -0.7 and -0.8 V, the sulfate-reducing bacteria can promote the electron transfer of cathode biofilm and enhance the acetate production. (C) 2017 Elsevier Ltd. All rights reserved.