Expression Analysis of Geobacter sulfurreducens Current-Consuming Biofilm versus No-Current Biofilm. Geobacter sulfurreducens

There is a wide diversity of potential applications for direct electron transfer from electrodes to microorganisms, which might be better optimized if the mechanisms for this novel electrode-biofilm interaction were further understood. Geobacter sulfurreducens is one of the few microorganisms available in pure culture that is known to be capable of directly accepting electrons from a negatively poised electrode. Gene transcript abundance in cells of G. sulfurreducens using electrons delivered from a graphite electrode as the sole electron donor for fumarate reduction was compared with transcript abundance in cells growing on the same graphite material, but without an electrical connection and acetate as the electron donor. Overall design: Wild type G. sulfurreducens was inoculated into a anaerobic, dual-chambered electrode system with the working electrode poised using a potentiostat at -500 mV (vs. Ag/AgCl) in order to serve as the electron donor and fumarate (40 mM) provided as the electron acceptor. An identical system in which the working electrode was left disconnected (no-current biofilm), with acetate provided as the electron donor and fumarate as the electron acceptor, served as the control. Both the experimental and control biofilms were harvested for RNA extraction once fully grown.