Prolonged production of hydrogen gas by a chloroplast biocatalytic system.

The evolution of H₂ gas in an $\text{in vitro}$ illuminated chloroplast plus hydrogenase system was shown to function for six and a half hours at a continuous rate of about 10 μmoles H₂/mg. chlorophyll/hour. Chloroplasts from various plant species, using different isolation media, and storage in a fixed state (glutaraldehyde) at 4°, ?5° and ?196° were shown to catalyze H₂ production. Both $\text{Clostridium}$ and $\text{E. coli}$ hydrogenase were used. From the use of the photosystem II inhibitors DCMU and DBMIB and heat inactivation of photosystem II, it was concluded that H₂O was the source of electrons for H₂ gas production.