S110: Biohydrogen production near 100°C

The archaeon Pyrococcus furiosus is a strictly anaerobic microorganism that grows in shallow marine volcanic vents at temperatures near 100°C.  It produces hydrogen gas during growth using both simple and complex carbohydrates as its carbon and energy sources.  The organism is being used as a model system to study biohydrogen production near the normal boiling point.  The reversible interconversion of hydrogen gas, protons and electrons, is catalyzed by a nickel-iron containing enzyme termed hydrogenase.  Three different types of hydrogenase have been characterized from P. furiosus. Hydrogenase I and hydrogenase II are located in the cytoplasm, utilize NADP(H) as an electron carrier and are thought to recycle hydrogen for biosynthetic purposes.  The third hydrogenase, termed MBH, is an integral membrane protein complex that functions as a novel respiratory system by reducing protons to hydrogen and by conserving energy in the form of a proton gradient. Results from recent studies will be presented on the recombinant production of the P. furiosus hydrogenases and their utility in biohydrogen production systems.