title: Graphene oxide-dependent growth and self-aggregation into a hydrogel complex of exoelectrogenic bacteria.
abstract: Graphene oxide (GO) is reduced by certain exoelectrogenic bacteria, but its effects on bacterial growth and metabolism are a controversial issue. This study aimed to determine whether GO functions as the terminal electron acceptor to allow specific growth of and electricity production by exoelectrogenic bacteria. Cultivation of environmental samples with GO and acetate as the sole substrate could specifically enrich exoelectrogenic bacteria with Geobacter species predominating (51-68% of the total populations). Interestingly, bacteria in these cultures self-aggregated into a conductive hydrogel complex together with biologically reduced GO (rGO). A novel GO-respiring bacterium designated Geobacter sp. strain R4 was isolated from this hydrogel complex. This organism exhibited stable electricity production at >1000 μA/cm(3) (at 200 mV vs Ag/AgCl) for more than 60 d via rGO while temporary electricity production using graphite felt. The better electricity production depends upon the characteristics of rGO such as a large surface area for biofilm growth, greater capacitance, and smaller internal resistance. This is the first report to demonstrate GO-dependent growth of exoelectrogenic bacteria while forming a conductive hydrogel complex with rGO. The simple put-and-wait process leading to the formation of hydrogel complexes of rGO and exoelectrogens will enable wider applications of GO to bioelectrochemical systems.
authors.affiliation: Center for Fostering Young and Innovative Researchers, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan.|Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Yoshida
authors.affiliation: Nagoya Municipal Industrial Research Institute, Nagoya, Aichi 456-0058, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Miyata
authors.affiliation: Department of Civil Engineering, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan.
authors.forename: Kasumi
authors.initials: K
authors.lastname: Doi
authors.affiliation: Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.|Department of Biomedical Science, College of Life and Health Science, Chubu University, Kasugai, Aichi 487-8501, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Goto
authors.affiliation: Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagao
authors.affiliation: Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.|Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Ryugo
authors.initials: R
authors.lastname: Tero
authors.affiliation: Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.|Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hiraishi
mesh_terms: D001674:Bioelectric Energy Sources; D018441:Biofilms; D025802:Electric Capacitance; D045302:Geobacter / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D006108:Graphite / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D058889:Molecular Typing; D010087:Oxides / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D020100:Hydrogels; D010087:Oxides; D012336:RNA, Ribosomal, 16S; D006108:Graphite