title: Quantification of electron transfer rates to a solid phase electron acceptor through the stages of biofilm formation from single cells to multicellular communities.
abstract: Microbial fuel cell (MFC) technology has enabled new insights into the mechanisms of electron transfer from dissimilatory metal reducing bacteria to a solid phase electron acceptor. Using solid electrodes as electron acceptors enables quantitative real-time measurements of electron transfer rates to these surfaces. We describe here an optically accessible, dual anode, continuous flow MFC that enables real-time microscopic imaging of anode populations as they develop from single attached cells to a mature biofilms. We used this system to characterize how differences in external resistance affect cellular electron transfer rates on a per cell basis and overall biofilm development in Shewanella oneidensis strain MR-1. When a low external resistance (100 Omega) was used, estimates of current per cell reached a maximum of 204 fA/cell (1.3 x 10(6) e(-) cell(-1) sec(-1)), while when a higher (1 MOmega) resistance was used, only 75 fA/cell (0.4 x 10(6) e(-) cell(-1) sec(-1)) was produced. The 1 MOmega anode biomass consistently developed into a mature thick biofilm with tower morphology (>50 microm thick), whereas only a thin biofilm (<5 microm thick) was observed on the 100 Omega anode. These data suggest a link between the ability of a surface to accept electrons and biofilm structure development.
authors.affiliation: The J. Craig Venter Institute, San Diego, CA, USA. jmclean@jcvi.org
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: McLean
authors.forename: Greg
authors.initials: G
authors.lastname: Wanger
authors.forename: Yuri A
authors.initials: YA
authors.lastname: Gorby
authors.forename: Martin
authors.initials: M
authors.lastname: Wainstein
authors.forename: Jeff
authors.initials: J
authors.lastname: McQuaid
authors.forename: Shun' Ichi
authors.initials: SI
authors.lastname: Ishii
authors.forename: Orianna
authors.initials: O
authors.lastname: Bretschger
authors.forename: Haluk
authors.initials: H
authors.lastname: Beyenal
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Nealson
mesh_terms: D001674:Bioelectric Energy Sources; D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D015169:Colony Count, Microbial; D017097:Electric Impedance; D004560:Electricity; D004563:Electrochemistry; D004566:Electrodes; D004583:Electrons; D020592:Shewanella / Q000166:cytology* / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D013997:Time Factors