Step towards sustainable hydrogen production with cyanobacteria

Under certain conditions, cyanobacteria (also known colloquially as "blue-green algae") are able to produce hydrogen using photosynthesis - a promising approach for generating clean energy. However, the oxygen produced during photosynthesis inhibits the activity of certain enzymes, so-called hydrogenases, which are necessary for hydrogen production. Previous approaches to oxygen removal were either inefficient or required the use of additional chemicals and carbohydrates, which impaired the sustainability of the process.

Protection enables continuous hydrogen production

The team led by Prof. Dr. Wolfgang Schuhmann from Bochum, Prof. Dr. Kirstin Gutekunst from Kassel and Dr. Felipe Conzuelo from Lisbon has now found a solution: By integrating cyanobacteria mutants into a special redox polymer deposited on an electrode, the cells can be protected from oxygen. The polymer contains viologen groups that are reduced by applying an electrical potential and thus efficiently break down the oxygen in the cells' environment.

The system creates an oxygen-free microenvironment directly around the cells so that the hydrogenases remain active and can continuously produce hydrogen. "This is an important step towards sustainable and scalable biotechnological hydrogen production," says the research team.

Genetically optimized cyanobacteria increase efficiency

The use of genetically modified cyanobacteria was particularly successful. In these mutants, the hydrogenase is genetically linked directly to the so-called photosystem I of photosynthesis. These mutants showed significantly longer and more stable hydrogen production compared to wild-type cells in the polymer.

Biophotovoltaics for the production of green hydrogen

The results of the study open up new possibilities for the development of bio-photovoltaic systems that convert sunlight directly into hydrogen. "Our approach combines the advantages of living cells - such as self-repair and longevity - with the precision of electrochemical systems," says Kirstin Gutekunst.