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Researchers engineered E. coli to have enhanced affinity to gold, resulting in improved performance in microbial fuel cells (MFCs). The engineered strains produced higher peak voltages and power densities compared to unengineered strains. The study demonstrates the potential of controlling microorganism surface affinity for improved bioelectrochemical system performance.

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What they did

System
MFC

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Abstract

Microorganism affinity for surfaces can be controlled by introducing material binding motifs into proteins such as fimbrial tip and outer membrane proteins. Here, controlled surface affinity is used to manipulate and enhance electrical power production in a typical bioelectrochemical system, a microbial fuel cell (MFC). Specifically, gold-binding motifs of various affinity were introduced into two scaffolds in Escherichia coli: eCPX, a modified version of outer membrane protein X (OmpX), and FimH, the tip protein of the fimbriae. The behavior of these strains on gold electrodes was examined in small-scale (240 µL) MFCs and 40 mL U-tube MFCs. A clear correlation between the affinity of a strain for a gold surface and the peak voltage produced during MFC operation is shown in the small-scale MFCs; strains displaying peptides with high affinity for gold generate potentials greater than 80 mV while strains displaying peptides with minimal affinity to gold produce potentials around 30 mV. In the larger MFCs, E. coli strains with high affinity to gold exhibit power densities up to 0.27 mW/m², approximately a 10-fold increase over unengineered strains lacking displayed peptides. Moreover, in the case of the modified FimH strains, this increased power production is sustained for five days.

Key findings

  • A clear correlation between gold surface affinity and peak voltage production was observed in small-scale MFCs.
  • Strains with high gold affinity generated potentials greater than 80 mV, while those with minimal affinity produced potentials around 30 mV.
  • In larger MFCs, engineered strains with high gold affinity exhibited power densities up to 0.27 mW/m², a 10-fold increase over unengineered strains.

Keywords

Microbial fuel cellEscherichia coliFimbriaBacterial outer membraneStrain (injury)Biophysics

Identifiers

DOI
10.3390/en14175389
Journal
Energies
Year
2021