Selective Growth of and Electricity Production by Marine Exoelectrogenic Bacteria in Self-Aggregated Hydrogel of Microbially Reduced Graphene Oxide

Graphene oxide (GO) has been shown to be reduced by several microorganisms. Recent studies of the growth of Geobacter species in the presence of GO and electricity production by recovery of electrons on the reduced form of GO (rGO) have indicated substantial benefits of GO and GO-respiring bacteria (GORB) in microbial electrochemical systems. In this study, we enriched GORB from a coastal sample to investigate the distribution and phylogenetic variety of GORB in seawater environments. X-ray photoelectron spectroscopy (XPS) and four-terminal probing revealed that the enriched microbial community (designated as CS culture) reduced GO and self-aggregated into a conductive hydrogel complex with rGO (the CS-rGO complex). In the process of GO reduction, certain bacterial populations grew in a manner that was dependent on GO respiration coupled with acetate oxidization. High-throughput sequencing of 16S rRNA as a biomarker revealed the predominance of Desulfomonas species at 92% of the total bacterial population in the CS culture. The CS-rGO complex produced electricity with acetate oxidization, exhibiting less than 1 Omega/cm(3) of charge transfer resistance. Thus, these results suggested that Desulfomonas species could grow on rGO and produce electricity via the reduced form of GO.