Plant Cell Physiology and Biotechnology Group

Hydrogen metabolism in cyanobacteria

Maximizing H2 production in the cyanobacterium



Hydrogen (H2) is a valuable and environmentally friendly energy carrier as it reacts in the well known “Knallgas-reaction” with oxygen to pure water and energy (Figure 1).


Figure 1: Conversion of hydrogen (H2) and oxygen (O2) to water (H2O) and energy.


Technologies that use H2 in fuel cells as an alternative energy source for e.g. cars are rather advanced. However, the production of hydrogen is still primarily based on the combustion of fossil fuels and therefore not CO2 neutral. 

Cyanobacteria are bacteria that invented oxygenic photosynthesis. Some of them possess a hydrogenase, which is an enzyme that catalyzes both the production and the consumption of H2. Strikingly, under certain conditions cyanobacteria use the energy of sunlight via photosynthesis to produce H2. The energy of sunlight that hits our planet exceeds by far our demand for energy. An approach that exploits sunlight for the production of H2 with H2 that is further used to provide energy and pure water is thus a most sustainable and environmentally friendly technique. No CO2 is produced in this process.

Figure 2: Photosynthetic electron transport in cyanobacteria. The hydrogenase (H2ase) receives electrons from ferredoxin (Fdx) at Photosystem I (PSI) to generate hydrogen (H2)


The organism of our studies is the cyanobacterium Synechocystis sp PCC 6803. It was the first photoautotroph whose genome was completely sequenced back in 1996. It is unicellular and its genome can be manipulated easily.

We aim to understand the physiology of hydrogen production in cyanobacteria in detail and to manipulate the cells in a manner that maximizes hydrogen production. This includes the photosynthetic electron transfer, the central carbohydrate metabolism and the biochemistry of the hydrogenase.