Abstract: A method of using sequential chemostat culture vessels to provide continuous H2 production, in which photosynthetic O2 evolution and H2 photoproduction are separated physically into two separate bioreactors, comprising: a) growing a microorganism culture able to continuously generate H2 by photosynthetically producing cells at about the early-to-late log state in a first photobioreactor operating as a sulfur chemostat under aerobic and/or conditions; b) continuously feeding cells from the first photobioreactor to a second photobioreactor operating under anaerobic conditions and sulfur deprivation conditions resulting from constant uptake of sulfate in the first bioreactor and a low rate of culture flow between the first and second bioreactors, for induction of hydrogenase and H2 photoproduction to allow for continuous cultivation of the microorganism's cells in the first photobioreactor and constant H2 production in the second photobioreactor, and c) H2 gas from the second photobioreactor.

Abstract: The invention provides oxygen- resistant iron-hydrogenases ([Fe]-hydrogenases) for use in the production of H2. Methods used in the design and engineering of the oxygen-resistant [Fe]-hydrogenases are disclosed, as are the methods of transforming and culturing appropriate host cells with the oxygen-resistant [Fe]-hydrogenases. Finally, the invention provides methods for utilizing the transformed, oxygen insensitive, host cells in the bulk production of H2 in a light catalyzed reaction having water as the reactant.

Abstract: A process for selection of oxygen-tolerant, H.sub.2 -producing algal mutant cells comprising:(a) growing algal cells photoautotrophically under fluorescent light to mid log phase;(b) inducing algal cells grown photoautrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas; (2) incubating the suspension in the absence of light at ambient temperature;(c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light.(d) washing off metronidazole and sodium azide to obtain final cell suspension;(e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear;(f) counting the number of colonies to determine the percent of mutant survivors; and(g) testing survivors to identify oxygen-tolerant H.sub.2 -producing mutants.