title: Sustained H₂ production in a Chlamydomonas reinhardtii D1 protein mutant.
abstract: In the present investigation, a detailed biochemical analysis of the high H₂ producer D1 protein mutant strain L159I-N230Y of Chlamydomonas reinhardtii, carrying a double amino acid substitution, was made. The leucine residue L159 was replaced by isoleucine, and the N230 asparagine was replaced by tyrosine. The performance of this strain was compared to that of the cc124 strain. The mutant showed a sustained capacity to donate electrons by means of direct biophotolysis for H₂ production, as demonstrated by the higher efficiency of utilization of the hydrogenase enzyme when carried out under anaerobic conditions. The latter property was maintained also under sulfur deprivation. Furthermore, when compared to the cc124, the mutant showed a higher amount of D1 protein content, a higher carbohydrate storage capacity and a sustained PSII direct contribution to the H₂ production during sulfur deprivation. The addition of DCMU to the cells showed that as much as 7.0 mL H₂ liter of culture h⁻¹ were produced by means of direct biophotolysis. The maximum apparent light-to-hydrogen conversion efficiency expressed on PAR (photosynthetically active radiation) reached 3.22%, while PSII efficiency to perform direct biophotolysis was calculated to be 2.03%. These values are significantly higher than what has been reported in the literature.
authors: Istituto per lo Studio degli Ecosistemi del Consiglio Nazionale delle Ricerche (CNR-ISE), Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Firenze, Italy.
authors: Alberto
authors: A
authors: Scoma
authors: Danuta
authors: D
authors: Krawietz
authors: Cecilia
authors: C
authors: Faraloni
authors: Luca
authors: L
authors: Giannelli
authors: Thomas
authors: T
authors: Happe
authors: Giuseppe
authors: G
authors: Torzillo
mesh_terms: D015153:Blotting, Western; D050260:Carbohydrate Metabolism / Q000187:drug effects; D016825:Chlamydomonas reinhardtii / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004237:Diuron / Q000494:pharmacology; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D055668:Photochemical Processes / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000235:genetics* / Q000276:immunology; D013455:Sulfur / Q000172:deficiency
chemical_list: D045332:Photosystem II Protein Complex; D013455:Sulfur; D006859:Hydrogen; D004237:Diuron; D006864:Hydrogenase