Multiple Paths for Hydrogen Production by the Cyanobacterium Cyanothece

Cyanobacteria are among the most ancient organisms on earth.

The Science

Many microbes can use solar energy to produce hydrogen. Researchers at Purdue University have now shown that a common photosynthetic ocean cyanobacterium, Cyanothece, can produce hydrogen by either direct reduction of protons using a hydrogenase enzyme or as a byproduct of conversion of nitrogen gas to ammonia (i.e. nitrogen fixation) by nitrogenase. Using a systems biology approach, the researchers demonstrated that genes and proteins involved in these distinct hydrogen production routes are coupled to separate branches of the cellular photosynthesis apparatus and are controlled by different regulatory systems that sense both light and nitrogen availability. The results of this study have been used to establish optimal bioreactor conditions and provide a number of promising metabolic engineering targets to enhance rates and yields of microbial hydrogen production.


Cyanothece sp. strain ATCC 51142 has a versatile metabolism and can grow in the presence or absence of combined nitrogen and can grow photosynthetically or mixotrophically and heterotrophically in the presence of glycerol. The highest rates of hydrogen production were produced under nitrogen-fixing conditions when cells were grown and incubated under continuous light conditions, in either the presence or absence of glycerol. Under such nitrogen-fixing conditions, researchers have achieved rates of 300 μmol H2/mg chloramphenicol (Chl)/hr during the first 24 h of incubation.

Principal Investigator

Louis A. Sherman
Purdue University


Min, H. and L. A. Sherman. 2010. “Hydrogen Production by the Unicellular, Diazotrophic Cyanobacterium Cyanothece sp. Strain ATCC 51142 under Conditions of Continuous Light,Applied and Environmental Microbiology 76, 4293–301. DOI:10.1128/AEM.00146-10.