The biological starting point
Photosynthesis converts solar energy into chemical energy. Water splitting supplies electrons and protons and releases oxygen; the captured energy normally helps support carbon fixation and metabolism.
Hydrogenase enzymes can instead combine electrons and protons to make molecular hydrogen. Bringing these reactions together is difficult because oxygen produced by photosynthesis inhibits many efficient hydrogenases, and competing metabolic reactions draw away the electron supply.
Photosynthetic electron focusing
PhotoSynH2 aims to engineer cyanobacteria with new genetic functions that connect water splitting to hydrogen production. We call this approach photosynthetic electron focusing.
The work combines three linked tasks:
- Redirect electron flow: re-engineer photosynthetic and metabolic pathways to increase the supply of electrons for hydrogen production.
- Manage oxygen: develop biological strategies that reduce inhibition of the hydrogen-producing enzymes.
- Build effective control: design and evolve proteins, gene regulators and RNA-based regulators to coordinate the engineered system.
From the laboratory to cultivation systems
The programme includes adapting the bacteria for growth in seawater and wastewater and improving their use of solar energy in larger photobioreactors. Reactor engineering addresses light delivery, cultivation conditions and the operation of contained biological systems.
The intended demonstration connects the engineered bacteria with a large-scale photobioreactor plant. The project’s estimated hydrogen cost of around €5/kg is a theoretical projection for the proposed process, to be evaluated through the research and engineering work.
Research you can read
Our publication collection covers hydrogenases, photobioreactors, biological hydrogen production and genetic engineering tools developed by consortium members.
PhotoSynH2 is coordinated by Alfonso Jaramillo at CSIC’s i2SysBio and funded by the European Union through EIC Pathfinder, grant agreement 101070948.