This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fouchard, S. Articles by Cournac, L. Search for Related Content PubMed PubMed Citation Articles by Fouchard, S. Articles by Cournac, L. Agricola Articles by Fouchard, S. Articles by Cournac, L.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, October 2005, p. 6199-6205, Vol. 71, No. 10
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.10.6199-6205.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Autotrophic and Mixotrophic Hydrogen Photoproduction in Sulfur-Deprived Chlamydomonas Cells

Laboratoire GEPEA, UMR CNRS-6144, Département de Physique, Faculté des Sciences et Techniques, 2 Rue de la Houssinière, BP 92208, F-44322 Nantes, France,¹ CEA Cadarache, DSV DEVM Laboratoire d'Ecophysiologie de la Photosynthèse, UMR 6191 CNRS-CEA, Aix-Marseille II, F-13108 Saint Paul Lez Durance, France,² Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Fakultät für Biologie, Ruhr Universität Bochum, D-44780 Bochum, Germany³

Received 17 January 2005/ Accepted 22 April 2005

In Chlamydomonas reinhardtii cells, H₂ photoproduction can be induced in conditions of sulfur deprivation in the presence of acetate. The decrease in photosystem II (PSII) activity induced by sulfur deprivation leads to anoxia, respiration becoming higher than photosynthesis, thereby allowing H₂ production. Two different electron transfer pathways, one PSII dependent and the other PSII independent, have been proposed to account for H₂ photoproduction. In this study, we investigated the contribution of both pathways as well as the acetate requirement for H₂ production in conditions of sulfur deficiency. By using 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), a PSII inhibitor, which was added at different times after the beginning of sulfur deprivation, we show that PSII-independent H₂ photoproduction depends on previously accumulated starch resulting from previous photosynthetic activity. Starch accumulation was observed in response to sulfur deprivation in mixotrophic conditions (presence of acetate) but also in photoautotrophic conditions. However, no H₂ production was measured in photoautotrophy if PSII was not inhibited by DCMU, due to the fact that anoxia was not reached. When DCMU was added at optimal starch accumulation, significant H₂ production was measured. H₂ production was enhanced in autotrophic conditions by removing O₂ using N₂ bubbling, thereby showing that substantial H₂ production can be achieved in the absence of acetate by using the PSII-independent pathway. Based on these data, we discuss the possibilities of designing autotrophic protocols for algal H₂ photoproduction.

This article has been cited by other articles:

• Surzycki, R., Cournac, L., Peltier, G., Rochaix, J.-D. (2007). Potential for hydrogen production with inducible chloroplast gene expression in Chlamydomonas. Proc. Natl. Acad. Sci. USA 104: 17548-17553 [Abstract] [Full Text]