Nanowired electrodes as outer membrane cytochrome-independent electronic conduit in Shewanella oneidensis

David Rehnlund; Guiyeoul Lim; Laura-Alina Philipp; Johannes Gescher

doi:10.1016/j.isci.2022.103853

Nanowired electrodes as outer membrane cytochrome-independent electronic conduit in Shewanella oneidensis

iScience. 2022 Jan 31;25(2):103853. doi: 10.1016/j.isci.2022.103853. eCollection 2022 Feb 18.

Authors

David Rehnlund^{1

2}, Guiyeoul Lim¹, Laura-Alina Philipp^{1

3}, Johannes Gescher^{1

4

3}

Affiliations

¹ Karlsruhe Institute of Technology (KIT), Institute for Applied Biosciences (IAB), Fritz-Haber-Weg 2, 76131, Karlsruhe, Germany.
² Uppsala University, Department of Chemistry - Ångström, Box 538, 75121, Uppsala, Sweden.
³ Hamburg University of Technology, Institute of Technical Microbiology, Kasernenstraße 12, 21073 Hamburg, Germany.
⁴ Karlsruhe Institute of Technology (KIT), Institute for Biological Interfaces (IBG 1), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.

Abstract

Extracellular electron transfer (EET) from microorganisms to inorganic electrodes is a unique ability of electrochemically active bacteria. Despite rigorous genetic and biochemical screening of the c-type cytochromes that make up the EET network, the individual electron transfer steps over the cell membrane remain mostly unresolved. As such, attempts to transplant entire EET chains from native into non-native exoelectrogens have resulted in inferior electron transfer rates. In this study we investigate how nanostructured electrodes can interface with Shewanella oneidensis to establish an alternative EET pathway. Improved biocompatibility was observed for densely packed nanostructured surfaces with a low cell-nanowire load distribution during applied external forces. External gravitational forces were needed to establish a bioelectrochemical cell-nanorod interface. Bioelectrochemical analysis showed evidence of nanorod penetration beyond the outer cell membrane of a deletion mutant lacking all outer membrane cytochrome encoding genes that was only electroactive on a nanostructured surface and under external force.

Keywords: Biomaterials; Nanostructure; Nanotechnology.