Hydrogenase-based electrode for hydrogen sensing in a fermentation bioreactor.

Area of Science:

• Biotechnology
• Electrochemistry
• Materials Science

Background:

• Current hydrogen (H 2) sensors face limitations like noble metal use and high operating temperatures.
• Hydrogenase enzymes offer high affinity and selectivity for H 2 under mild conditions.

Purpose of the Study:

• To evaluate an electrochemical sensor using immobilized hydrogenase from Aquifex aeolicus on carbon nanomaterials for H 2 detection.
• To optimize sensor performance by investigating parameters like surface chemistry, enzyme concentration, temperature, and pH.

Main Methods:

• Fabrication of a bioelectrode using carbon nanotubes and immobilized A. aeolicus hydrogenase.
• Investigation of H 2 oxidation kinetics under varying conditions (temperature, pH, enzyme concentration).
• Development of a pulse strategy for enhanced H 2 diffusion and sensor response.

Main Results:

• Optimal catalytic response observed around 60 °C, with significant room temperature activity.
• Achieved H 2 sensitivity of 4 μA cm -2 per % H 2 with a linear range of 1-20%.
• The biosensor demonstrated insensitivity to CO 2 and H 2S, key byproducts of hydrogen fermentation.

Conclusions:

• The A. aeolicus hydrogenase-based biosensor is a promising, cost-effective, and sensitive tool for H 2 detection.
• The sensor's robustness against common fermentation byproducts makes it suitable for in situ monitoring in bioreactors.
• This technology supports the development of a sustainable hydrogen economy through efficient H 2 sensing.