Quantification of Electron Transfer Rates to a Solid Phase Electron Acceptor through the Stages of Biofilm Formation from Single Cells to Multicellular Communities

• Published in: Environmental science & technology Vol. 44; no. 7; pp. 2721 - 2727
• Main Authors: McLean, Jeffrey S, Wanger, Greg, Gorby, Yuri A, Wainstein, Martin, McQuaid, Jeff, Ishii, Shun’ ichi, Bretschger, Orianna, Beyenal, Haluk, Nealson, Kenneth H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.04.2010
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Bacteria; Bioelectric Energy Sources; Biofilms; Biofilms - growth & development; Biological and medical sciences; Biomass; Cells; Colony Count, Microbial; Ecotoxicology, biological effects of pollution; Electric Impedance; Electricity; Electrochemistry; Electrodes; Electron transfer; Electrons; Energy and the Environment; Exact sciences and technology; Fuel cells; Fundamental and applied biological sciences. Psychology; General aspects; Pollution; Real time; Shewanella - cytology; Shewanella - growth & development; Shewanella - physiology; Shewanella - ultrastructure; Shewanella oneidensis; Time Factors; Biofilm; Electron transfer; Solid phase; Electron acceptor; Community
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es903043p

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 Ω) was used, estimates of current per cell reached a maximum of 204 fA/cell (1.3 × 106 e− cell−1 sec−1), while when a higher (1 MΩ) resistance was used, only 75 fA/cell (0.4 × 106 e− cell−1 sec−1) was produced. The 1 MΩ anode biomass consistently developed into a mature thick biofilm with tower morphology (>50 μm thick), whereas only a thin biofilm (<5 μm thick) was observed on the 100 Ω anode. These data suggest a link between the ability of a surface to accept electrons and biofilm structure development.