Bacterium with Improved Hydrogen Production from Sunlight

The Science

One challenge to the commercialization of microbial production of hydrogen using sunlight is that the oxygen produced by photosynthesis decreases hydrogen production. Various biological mechanisms have evolved to separate the two reactions and scientists have been looking for engineering solutions, but the challenge is not yet solved. Scientists at the Pacific National Northwest Laboratory now have shown for the first time that a single-celled cyanobacterium, Cyanothece, is able to produce hydrogen and oxygen simultaneously without interruption for at least 100 hours. The bacteria produce hydrogen at relatively high rates without high cell density or inducing circadian rhythms, as required in studies by other researchers. Furthermore, there is little photo-damage and decay of the photosynthesis apparatus, perhaps enabled by the removal of excess electrons by the hydrogen production. These results and the improved understanding of the underlying cyanobacterial physiology will help advance the biotechnology of microbial hydrogen production.

The Impact

This work is also of significance for biotechnology, supporting the feasibility of “direct biophotolysis.” The sustainability of the process, highlighted by prolonged gas evolution with no clear sign of significant decay or apparent photodamage, provides a foundation for the future development of an effective, renewable, and economically efficient bio-H2 production process.


Melnicki, M. R., G. E. Pinchuk, E. A. Hill, L. A. Kucek, J. K. Fredrickson, A. Konopka, A. S. Beliaev. 2012. “Sustained H2 Production Driven by Photosynthetic Water Splitting in a Unicellular Cyanobacterium,” mBio 3(4), e00197-12. DOI:10.1128/mBio.00197-12.