Imagine a future where sunlight fuels not just our energy needs but also the creation of essential materials for everyday life—clean, efficient, and entirely sustainable. At the forefront of this revolutionary vision is a team of researchers at the University of Oxford’s Department of Engineering Science. They have achieved a significant breakthrough in the exploration of green hydrogen by bio-engineering bacteria to work as ‘hydrogen nanoreactors’. This innovative approach holds the potential to establish a cost-effective, zero-carbon method for producing hydrogen fuels.
Bio-Engineering to Hydrogen Nanoreactors
Hydrogen is poised to play a pivotal role in achieving net-zero emissions, as it combusts cleanly without releasing carbon dioxide. However, the predominant industrial methods for hydrogen production currently depend on fossil fuels. They result in nearly 11.5 to 13.6 KGs of CO₂ emissions per KG of hydrogen produced.
Enter the latest breakthrough, is built on the extensive expertise developed by Professor Huang’s lab in sustainable synthetic biology. In this innovative approach, researchers used bio-engineered bacteria known as “hydrogen nanoreactors” to create hydrogen fuel using water and sunlight. This groundbreaking study was published in the Proceedings of the National Academy of Science.
In 2023, his team achieved a world-first by successfully bio-engineering Ralstonia eutropha, a non-photosynthetic bacterium, to become photosynthetic—a pivotal milestone for the field. Like the Shewanella hydrogen nanoreactors, this system utilized rhodopsin, though in this case, it replaced chlorophyll, the pigment typically responsible for powering photosynthesis.
Synthetic Biology’s Masterstroke: Bionanoreactor
The Oxford research team employed synthetic biology techniques to transform the bacterium Shewanella oneidensis into a cellular ‘bionanoreactor’. This is capable of splitting water and producing hydrogen using sunlight. This method addresses a critical challenge in green hydrogen production by creating a highly efficient, stable, and cost-effective biocatalyst.
Lead author Professor Wei Huang highlighted the advantages of this biocatalyst, stating, “Our new study has the advantages of greater safety, renewability, and lower production costs. All these result in improving long-term economic viability.”
Professor Ian Thompson, a co-author from Oxford’s Department of Engineering Science, highlighted, “We aim to achieve efficient, affordable, and safe green hydrogen production.” Also, he said that their bionanoreactor demonstrates the potential of biocatalysts for clean energy generation.
Sustainable and Clean Hydrogen Production
In nature, certain microorganisms utilize hydrogenase enzymes to reduce protons (H⁺) to hydrogen gas (H₂). However, their effectiveness as hydrogen catalysts has been limited due to constraints such as low electron transfer rates.
To overcome these limitations, the researchers engineered Shewanella oneidensis to concentrate electrons, protons, and hydrogenase within the periplasmic space—the area between the bacterium’s inner and outer membranes, measuring 20-30 nanometers in width. This species is also well-recognized for its electroactive properties. It enables electron transfer to or from solid surfaces outside the cell.
To further enhance electron and proton transfer, the team incorporated a light-activated electron pump, Gloeobacter rhodopsin, into the inner membrane. This modification allows the bacterium to efficiently pump protons into the periplasm in the presence of light. Additionally, the researchers introduced the pigment canthaxanthin and engineered the Gloeobacter rhodopsin. Thereby pigment canthaxanthin absorbs light energy, and boosts proton pumping by harvesting extra photon energy from sunlight. The introduction of nanoparticles of reduced graphene oxide and ferric sulfate further enhanced electron transfer efficiency.
Weiming Tu, the first author of the study explained, “The natural periplasm of S. oneidensis provides an ideal nanoscale environment for hydrogen production.” It efficiently ‘compresses’ protons and electrons, enhancing their chances of interaction within these nanoscale spaces. From a thermodynamic perspective, this design reduces the energy needed for hydrogen production. It showcases an excellent example of engineering biology in action.
Creating Artificial Leaves to Generate Hydrogen
The researchers expect scaling up the system to create “artificial leaves” by printing the engineered cells onto carbon fiber cloth. Once exposed to sunlight, these artificial leaves would instantly begin generating hydrogen, offering a sustainable and efficient solution for clean energy production.
This achievement secured follow-on funding from UK Research and Innovation (UKRI) and Japan’s Science and Technology Agency (JST) to advance artificial photosynthetic cell systems for green biotechnology. In collaboration with Professor Hiroyuki Noji from the University of Tokyo, Professor Wei Huang is leading a partnership of eight universities from the UK and Japan. Their research focuses on sustainable methods to convert carbon dioxide into valuable bioproducts, such as biodegradable plastics. These innovations aim to provide environmentally friendly solutions for industries ranging from healthcare and biomanufacturing to agriculture.
Conclusion
This pioneering work represents a significant step toward sustainable and environmentally friendly hydrogen production. By leveraging bio-engineered bacteria as efficient hydrogen nanoreactors, the researchers have opened new avenues for clean energy generation. Thereby potentially transforming the landscape of renewable fuels.
In conclusion, the breakthrough transforms bacteria into hydrogen nanoreactors, marking a key step in clean energy research. These engineered bacteria use sunlight to produce hydrogen fuel, offering a promising, eco-friendly solution.
