title: A comparison of hydrogen photoproduction by sulfur-deprived Chlamydomonas reinhardtii under different growth conditions.
abstract: Continuous photoproduction of H(2) by the green alga, Chlamydomonas reinhardtii, is observed after incubating the cultures for about a day in the absence of sulfate and in the presence of acetate. Sulfur deprivation causes the partial and reversible inactivation of photosynthetic O(2) evolution in algae, resulting in the light-induced establishment of anaerobic conditions in sealed photobioreactors, expression of two [FeFe]-hydrogenases in the cells, and H(2) photoproduction for several days. We have previously demonstrated that sulfur-deprived algal cultures can produce H(2) gas in the absence of acetate, when appropriate experimental protocols were used (Tsygankov, A.A., Kosourov, S.N., Tolstygina, I.V., Ghirardi, M.L., Seibert, M., 2006. Hydrogen production by sulfur-deprived Chlamydomonas reinhardtii under photoautotrophic conditions. Int. J. Hydrogen Energy 31, 1574-1584). We now report the use of an automated photobioreactor system to compare the effects of photoautotrophic, photoheterotrophic and photomixotrophic growth conditions on the kinetic parameters associated with the adaptation of the algal cells to sulfur deprivation and H(2) photoproduction. This was done under the experimental conditions outlined in the above reference, including controlled pH. From this comparison we show that both acetate and CO(2) are required for the most rapid inactivation of photosystem II and the highest yield of H(2) gas production. Although, the presence of acetate in the system is not critical for the process, H(2) photoproduction under photoautotrophic conditions can be increased by optimizing the conditions for high starch accumulation. These results suggest ways of engineering algae to improve H(2) production, which in turn may have a positive impact on the economics of applied systems for H(2) production.
authors.affiliation: Institute of Basic Biological Problems RAS, Pushchino, Moscow Region 142290, Russia. sergks@ibbp.psn.ru
authors.forename: Sergey
authors.initials: S
authors.lastname: Kosourov
authors.forename: Elena
authors.initials: E
authors.lastname: Patrusheva
authors.forename: Maria L
authors.initials: ML
authors.lastname: Ghirardi
authors.forename: Michael
authors.initials: M
authors.lastname: Seibert
authors.forename: Anatoly
authors.initials: A
authors.lastname: Tsygankov
mesh_terms: D000085:Acetates / Q000378:metabolism; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000254:growth & development / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D006859:Hydrogen / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013455:Sulfur
chemical_list: D000085:Acetates; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D013455:Sulfur; D006859:Hydrogen; D013213:Starch; D010100:Oxygen; D000077194:Chlorophyll A