Characterizing the snorkeling respiration and growth of Shewanella decolorationis S12.

Microbial electrochemical snorkel (MES) reactor is a simplified bioreactor based on microbial fuel cells (MFCs) and has been suggested to be a promising approach to solve many environmental problems. However, the microbial processes in MES reactors have not yet been characterized. This study shows that Shewanella decolorationis S12 can use the conductive snorkel as direct electron acceptor for respiration and growth. Similar with current-generating biofilms, cellular viability in MES biofilms decreased with the distance from snorkel. MES reactors showed more rapid cell growth and substrate consumption than MFCs. Although the biomass density of MES biofilm was higher than that of anode biofilms, the current-generating capacity and electrochemical activity of MES biofilm were lower, which could be attributed to the lower cytochrome c expression in MES biofilm caused by the higher redox potential of MES. These microbiological and electrochemical properties are essential for the further development of MES reactors.