Most efficient producer of Biohydrogen to date discovered

A strain of Cyanobacteria has been found not only to be the most efficient hydrogen producing bacteria to date, but also to be able to produce it in the presence of oxygen. (A Bandyopadhyay et al, published in Nature Commun., 2010, DOI: 10.1038/ncomms1139).

The ocean dwelling Cyanobacteria Cyanothece 51142 has been found to be the most efficient producer of Biohydrogen, and can do so in the presence of oxygen. This is unusual, as the enzymes that produce hydrogen in most other species are inhibited and destroyed by even very low concentrations of oxygen. This makes the use of these organisms to produce hydrogen at any scale difficult, not to mention expensive. However, this is not the case for Cyanothece. High respiration rates protect the enzymes from damage by oxygen. The microbe is also photosynthetic, gathering the energy for the reaction directly from sunlight. 

Purdue University Researcher, Louis Sherman:

“We expected high rates of hydrogen production, but we were very surprised to find such high rates "right out of the box”. The strain has amazing capabilities and we think that there is still untapped potential. It will stimulate other biologists to keep studying photosynthetic microbes to find one with even better properties. And it will help policy makers realize that bio-hydrogen production is a possibility and enhance research into all of the other areas that need to be studied before a "hydrogen economy" is a reality.”

Cyanothece 51142 changes its metabolism between day and night; photosynthesizing during daylight to produce energy stored as glycogen, and at night it uses this energy to produce ammonia and hydrogen. The research group experimented with optimizing hydrogen production and found that additional carbon sources increases the amount of hydrogen produced. Many carbon sources are suitable for giving this reaction boost, including byproducts of biodiesel production such as glycerol.

 
What commercial opportunities does this open? Biohydrogen has been dismissed as impractical in many cases; often due to the energy needs of the microbes themselves and the high amounts of energy needed for the reaction, often resulting in low yields. However, early efforts to optimize the production of hydrogen from Cyanothece achieved yields more than ten times those achieved by the next best efforts. These developments and the potential for future developments may be worth re-assessing the value of Biohydrogen. However, in the face of much greater efforts to develop other sustainable fuels and a lack of existing infrastructure to support wide scale use of hydrogen fuel, any advances here are likely to be limited to existing markets for hydrogen rather than as a replacement for petrochemicals.