Impact of conductive magnetite nanoparticles and anode polarization on glucose fermentation

Abstract BACKGROUND Electrically conductive materials and electrochemical stimulation strategies are increasingly explored to steer microbial fermentation towards desired metabolic outputs. These approaches also hold remarkable potential to couple wastewater treatment (WWT) to the production of value‐added compounds, in turn enhancing environmental sustainability and bioresource recovery. In this study, the effect of either conductive magnetite nanoparticles (Fe 3 O 4 ‐NP S ) or anode electro‐fermentation (at +0.20 V vs. Standard Hydrogen Electrode) or, even, a combination thereof was explored as a means to steer glucose fermentation by mixed microbial cultures. RESULTS The combined application of anode polarization and magnetite nanoparticles resulted in an enhanced (up to nearly 25% on a molar basis) total production of carboxylic acids relative to unamended control tests. Remarkably, the addition of magnetite, irrespective of the presence of the polarized electrode, steered the metabolism towards an enhanced (up to 52% on a molar basis, relative to unamended control) accumulation of butyric acid (up to ~50 mmolC L −1 ) from glucose degradation. CONCLUSION This finding is relevant since butyric acid is a high‐value platform chemical with applications in the production of biofuels, bioplastics, and pharmaceuticals, making its selective biosynthesis of considerable industrial interest. Anode polarization alone contributed less significantly to changes in the relative distribution of organic acids. Overall, this study demonstrates how integrating conductive nanoparticles and electrochemical stimulation can be leveraged to manipulate mixed‐culture fermentations. © 2026 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).