Disparity of Cytochrome Utilization in Anodic and Cathodic Extracellular Electron Transfer Pathways of Geobacter sulfurreducens Biofilms

Nina Heidary, Nikolay Kornienko, Shafeer Kalathil, Xin Fang, Khoa H. Ly, Heather F. Greer, Erwin Reisner

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
12 Downloads (Pure)

Abstract

Extracellular electron transfer (EET) in microorganisms is prevalent in nature and has been utilized in functional bioelectrochemical systems. EET of Geobacter sulfurreducens has been extensively studied and has been revealed to be facilitated through c-type cytochromes, which mediate charge between the electrode and G. sulfurreducens in anodic mode. However, the EET pathway of cathodic conversion of fumarate to succinate is still under debate. Here, we apply a variety of analytical methods, including electrochemistry, UV-vis absorption and resonance Raman spectroscopy, quartz crystal microbalance with dissipation, and electron microscopy, to understand the involvement of cytochromes and other possible electron-mediating species in the switching between anodic and cathodic reaction modes. By switching the applied bias for a G. sulfurreducens biofilm coupled to investigating the quantity and function of cytochromes, as well as the emergence of Fe-containing particles on the cell membrane, we provide evidence of a diminished role of cytochromes in cathodic EET. This work sheds light on the mechanisms of G. sulfurreducens biofilm growth and suggests the possible existence of a nonheme, iron-involving EET process in cathodic mode.
Original languageEnglish
Pages (from-to)5194-5203
Number of pages10
JournalJournal of the American Chemical Society
Volume142
Issue number11
Early online date17 Feb 2020
DOIs
Publication statusPublished - 18 Mar 2020
Externally publishedYes

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