Development of an efficient algal H{sub 2}-producing system
- National Renewable Energy Lab., Golden, CO (United States)
The objectives of this effort are to generate O{sub 2}-tolerant, H{sub 2}-producing mutants from the green alga Chlamydomonas reinhardtii; test them in a laboratory-scale system for the continuous photo-production of H{sub 2} under aerobic conditions; and collaborate with Dr. Greenbaum at Oak Ridge National Laboratory (ORNL) to improve the efficiency of H{sub 2} production in intact and cell-free systems. Hydrogen production by green algae has the following significant advantages over other biological systems: ATP production is not required; high theoretical efficiencies are possible; and water is used as the source of reductant with no stored intermediary metabolites. The current practical limitations to using green algae in a photobiological H{sub 2}-producing system include the sensitivity of hydrogenases to O{sub 2}; the occurrence of a dark back reaction between O{sub 2} and H{sub 2} (i.e., the oxy-hydrogen reaction); competition between the CO{sub 2} reduction and the H{sub 2}-producing pathways for electrons from H{sub 2}O; the low equilibrium pressure of H{sub 2} release; and saturation of H{sub 2}-production at low light intensity. ORNL has been working extensively on the last issue. In this new initiative, we will address the hydrogenase O{sub 2}-sensitivity problem in Chlamydomonas reinhardtii by generating and selecting for O{sub 2}-tolerant, H{sub 2}-producing mutants. Our approach will involve treating cell suspensions of Chlamydomonas with a mutagen, followed by selection for growth under photoreducing conditions (which favor a functional, O{sub 2}-tolerant H{sub 2}-consuming hydrogenase), as well as for survival under conditions that favor a functional O{sub 2}-tolerant H{sub 2}-producing hydrogenase under increasing O{sub 2} stress. The dual approach will allow us to select for mutants that not only show increased O{sub 2} tolerance but may also exhibit decreased levels of the oxy-hydrogen back reaction.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 183301
- Report Number(s):
- NREL/CP-430-20036-Vol.2; CONF-9504160-VOL.2; ON: DE95009296; TRN: 95:008711-0013
- Resource Relation:
- Conference: 1995 DOE/NREL hydrogen program review, Coral Gables, FL (United States), 18-21 Apr 1995; Other Information: PBD: Sep 1995; Related Information: Is Part Of Proceedings of the 1995 US DOE hydrogen program review, Volume II; PB: 876 p.
- Country of Publication:
- United States
- Language:
- English
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