title: Deletion of Proton Gradient Regulation 5 (PGR5) and PGR5-Like 1 (PGRL1) proteins promote sustainable light-driven hydrogen production in Chlamydomonas reinhardtii due to increased PSII activity under sulfur deprivation.
abstract: Continuous hydrogen photo-production under sulfur deprivation was studied in the Chlamydomonas reinhardtii pgr5 pgrl1 double mutant and respective single mutants. Under medium light conditions, the pgr5 exhibited the highest performance and produced about eight times more hydrogen than the wild type, making pgr5 one of the most efficient hydrogen producer reported so far. The pgr5 pgrl1 double mutant showed an increased hydrogen burst at the beginning of sulfur deprivation under high light conditions, but in this case the overall amount of hydrogen produced by pgr5 pgrl1 as well as pgr5 was diminished due to photo-inhibition and increased degradation of PSI. In contrast, the pgrl1 was effective in hydrogen production in both high and low light. Blocking photosynthetic electron transfer by DCMU stopped hydrogen production almost completely in the mutant strains, indicating that the main pathway of electrons toward enhanced hydrogen production is via linear electron transport. Indeed, PSII remained more active and stable in the pgr mutant strains as compared to the wild type. Since transition to anaerobiosis was faster and could be maintained due to an increased oxygen consumption capacity, this likely preserves PSII from photo-oxidative damage in the pgr mutants. Hence, we conclude that increased hydrogen production under sulfur deprivation in the pgr5 and pgrl1 mutants is caused by an increased stability of PSII permitting sustainable light-driven hydrogen production in Chlamydomonas reinhardtii.
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Steinbeck
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Denitsa
authors.initials: D
authors.lastname: Nikolova
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Weingarten
authors.affiliation: Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Institut de Biologie Environnementale et de Biotechnologie, Direction des Sciences du Vivant, Commissariat à l'Energie Atomique et aux Energies Alternatives Saint-Paul-lez-Durance, France ; CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementale Saint-Paul-lez-Durance, France ; Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Aix Marseille Université Saint-Paul-lez-Durance, France.
authors.forename: Xenie
authors.initials: X
authors.lastname: Johnson
authors.affiliation: Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Institut de Biologie Environnementale et de Biotechnologie, Direction des Sciences du Vivant, Commissariat à l'Energie Atomique et aux Energies Alternatives Saint-Paul-lez-Durance, France ; CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementale Saint-Paul-lez-Durance, France ; Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Aix Marseille Université Saint-Paul-lez-Durance, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.affiliation: Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Institut de Biologie Environnementale et de Biotechnologie, Direction des Sciences du Vivant, Commissariat à l'Energie Atomique et aux Energies Alternatives Saint-Paul-lez-Durance, France ; CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementale Saint-Paul-lez-Durance, France ; Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, Aix Marseille Université Saint-Paul-lez-Durance, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Peltier
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Marita
authors.initials: M
authors.lastname: Hermann
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Magneschi
authors.affiliation: Institute of Plant Biology and Biotechnology, University of Münster Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hippler
keywords: PGR5; PGRL1; PSII stability; hydrogen production; sulfur deprivation