Paul van Gerven
15 March 2023

Researchers from Monash University Biomedicine Discovery Institute in Melbourne have discovered an enzyme that can ‘burn’ hydrogen to generate electricity. Extracted from a common soil bacterium, the complex protein called Huc is remarkably efficient: it can convert even trace amounts of the gas present in ambient air – a feat that no synthetic catalyst has been able to replicate. Huc could possibly be used in fuel cells or as a power source for low-energy devices.

Hydrogen-consuming bacteria are actually quite common in soil. In some cases, the ability appears to have evolved to serve as a backup power source when starvation sets in. Only in extremely nutrient-deprived environments, bacteria specialized in using H2 as fuel are found. These usually can’t tolerate exposure to high levels of oxygen, which ‘chokes’ their hydrogen-burning enzymes.

Huc enzyme
The atomic structure of the Huc enzyme. Credit: Rhys Grinter

Huc, found in M. smegmatis, is an exception. Even in the presence of 21 percent oxygen, it can consume hydrogen from the ambient air, which constitutes only 0.00005 percent of the gaseous mixture. For a piece of biological material, it’s also quite robust; it can be frozen or heated to 80 degrees Celsius without losing activity.

In a Nature paper, the Australian scientists elucidate the mechanism through which Huc oxidizes hydrogen, which means extracting electrons from it, and explain its insensitivity to oxygen. Armed with this knowledge, a synthetic analogue may be developed. Alternatively, the real thing could be used to build air-powered devices, although scaling the production process is challenging.

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