Advent Platinum Wire Enables First Demonstration of Anodic Electro-Fermentation in Bacillus subtilis

Advent’s platinum electrode wire played a vital role in Tampere University’s breakthrough on anodic electro-fermentation.
Using Bacillus subtilis engineered for enhanced electron transfer, researchers demonstrated a more efficient, oxygen-free process for producing valuable biochemicals.

The science made simple

Scientists at Tampere University wanted to find a cleaner way to make useful chemicals without using oxygen. Normally, tiny living cells called bacteria need oxygen to grow and turn sugars into products like alcohols or acids.
In this study, the researchers used a safe, common bacterium called Bacillus subtilis and found a way for it to work without oxygen.

They gave the bacteria a special surface—an electrode made with Advent’s platinum wire—that could accept the electrons the cells usually pass to oxygen. This let the bacteria keep working even in an oxygen-free environment.

By changing the pH and slightly editing the bacteria’s genes, the team made the process much faster and more efficient. The result was a big increase in how much of a valuable chemical, 2,3-butanediol, the bacteria could make.

It’s a new step toward producing everyday materials—like plastics and fuels—in a way that’s cleaner and less dependent on fossil resources.

Supporting innovation in bioelectrochemical research

At Tampere University, researchers are pioneering ways to make industrial biotechnology more sustainable. Their latest study explores how anodic electro-fermentation (AEF) can drive oxygen-free biochemical production using Bacillus subtilis, a widely used microorganism in enzyme and chemical manufacturing.

The research team relied on Advent’s platinum wire electrodes to provide the stable, conductive surface needed for precise electrochemical control in their custom-built bioelectrochemical reactors. The electrodes were essential to capturing electron flow from the engineered bacteria, enabling accurate measurement of current density and metabolic activity throughout the experiment.

The role of Advent’s platinum wire

Advent supplied the 10 cm × 0.4 mm platinum wire used as the cathode in the study’s three-electrode system.
Chosen for its high conductivity, corrosion resistance, and purity, the wire ensured reliable electron transfer and consistent data across prolonged anaerobic tests.

In this setup, the platinum cathode worked alongside a carbon felt anode and cation exchange membrane to complete the anodic electro-fermentation circuit. Its precision and performance allowed researchers to assess how modifications to Bacillus subtilis metabolism—and control of pH—affected the efficiency of electron transfer.

Experiment overview

The team genetically modified Bacillus subtilis by deleting the ldh gene, which normally drives NAD⁺ regeneration during fermentation. This change redirected electron flow toward the anode, making the process dependent on external electron transfer rather than oxygen.

Using Advent platinum electrodes within H-type borosilicate reactors, the researchers maintained a controlled anodic potential and measured current output as a direct indicator of extracellular electron transfer.
The system also incorporated potassium ferricyanide as a mediator to facilitate electron movement between cells and the electrode.

Results and impact

The study achieved a 35-fold increase in current density, with a peak of 0.77 mA/cm² reached within two hours.
Controlling the pH proved critical to performance:

• At pH 6.5, the system achieved 77 % selectivity for 2,3-butanediol, a key industrial compound.
• At pH 7.5, glucose consumption reached 89 %, and total charge transfer peaked.

These results confirmed that Bacillus subtilis could sustain anodic respiration—a milestone for a species previously limited to oxygen-dependent processes. The findings also highlight the potential of electrochemical control in producing high-value chemicals with reduced environmental impact.

Enabling cleaner biochemical production

The use of Advent’s platinum electrodes provided the accuracy, purity, and consistency required for a study of this precision.
By helping researchers monitor electron transfer under strict anaerobic conditions, the electrodes supported the discovery of a more energy-efficient, oxygen-free route for producing 2,3-butanediol and related compounds.

This work demonstrates how high-quality research materials from Advent continue to enable leading laboratories to explore new methods of sustainable manufacturing, from biocatalysis to electrochemical system design.

Advent Research Materials is proud to have supplied the platinum electrode wire used in this groundbreaking work at Tampere University.

The study shows how robust, high-purity metals underpin advances in bioelectrochemistry—supporting innovation in renewable biochemical production and next-generation fermentation technologies.

Read the full study

This research was carried out at Tampere University, Finland, by Yu Sun, Changshuo Liu, Igor Vassilev, Antti J. Rissanen, Jin Luo, and Marika Kokko.
The study, “Enhanced extracellular respiration of engineered Bacillus subtilis via anodic electro-fermentation with pH optimisation,” is currently published as a preprint on Research Square and is under peer review for Biotechnology for Biofuels and Bioproducts.

Citation:
Sun Y., Liu C., Vassilev I., Rissanen A.J., Luo J., & Kokko M. (2025). Enhanced extracellular respiration of engineered Bacillus subtilis via anodic electro-fermentation with pH optimisation. Research Square Preprint.
DOI: 10.21203/rs.3.rs-7808705/v1

Status: Preprint — under review at Biotechnology for Biofuels and Bioproducts
License: Creative Commons Attribution 4.0 (CC BY 4.0)

Readers can access and share the open-access version on the Research Square website.