1. The hydrogen metabolism of sulfur deprived Chlamydomonas reinhardtii cells involves hydrogen uptake activities
- Author
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Anja Hemschemeier and Alberto Scoma
- Subjects
H-2 partial pressure ,PHOTOSYSTEM-II ACTIVITY ,0106 biological sciences ,0301 basic medicine ,CALVIN CYCLE ,Chlamydomonas reinhardtii ,Photobioreactor ,H-2 uptake ,Photosynthesis ,01 natural sciences ,GREEN-ALGA ,CARBON-DIOXIDE ,03 medical and health sciences ,Algae ,Green algae ,Ferredoxin ,Glycolaldehyde ,biology ,D1 PROTEIN ,Chlamydomonas ,PHOTOSYNTHETIC ELECTRON-TRANSPORT ,Metabolism ,PYRUVATE FERREDOXIN OXIDOREDUCTASE ,biology.organism_classification ,TUBULAR PHOTOBIOREACTOR ,Electron transport chain ,030104 developmental biology ,Biochemistry ,Agronomy and Crop Science ,OXYHYDROGEN REACTION ,H-2 PRODUCTION ,010606 plant biology & botany - Abstract
Several species of unicellular microalgae such as the model species Chlamydomonas reinhardtii possess plastid-localized [FeFe]-hydrogenases which, via ferredoxin, can accept electrons from photosynthetic electron transport. Thereby, under specific conditions, these algae light-dependently produce molecular hydrogen (H 2 ), which offers a sustainable way to generate a “green” and efficient fuel. Until today, the most common way to induce sustained H 2 production is to deprive Chlamydomonas of macronutrients such as sulfur (S) which results in a downregulation of photosynthetic production of molecular oxygen (O 2 ) and of assimilatory processes. These acclimation responses allow the O 2 sensitive algal [FeFe]-hydrogenases to become active and serve as an alternative electron sink of photosynthesis. Despite much progress in the field and a general understanding of the underlying mechanisms, many basic and applied aspects of the photosynthetic H 2 metabolism of eukaryotic algae remain to be elucidated. One rarely investigated factor is that microalgae have also been reported to consume H 2 , especially as a response to high H 2 concentrations. Here, we analyzed the H 2 uptake activities of S-deprived Chlamydomonas cells incubated in different PBRs providing different gas phase volumes, either in continuous light or in the dark. We show that H 2 uptake occurs after prolonged incubation in the light as well as in sudden darkness. Dark-induced H 2 uptake can be delayed adding the phosphoribulose kinase inhibitor glycolaldehyde, suggesting a connection to carbohydrate metabolism. The results indicate that PBR setups as well as envisioned outdoor cultivation systems with natural light-dark cycles have to be carefully designed to prevent efficiency losses. more...
- Published
- 2017
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