Acclimation to hypoxia in Chlamydomonas reinhardtii: can biophotolysis be the major trigger for long‐term H2 production?. Issue 4 (8th August 2014)

• Record Type: Journal Article
• Authors: Scoma, Alberto; Durante, Lorenzo; Bertin, Lorenzo; Fava, Fabio
• Is Part Of: New phytologist. Volume 204:Issue 4(2014)
• Page Start: 890
• Page End: 900
• Publication Date: 2014-08-08
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12964
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12964-abs-0001"> <title>Summary</title> <p> <list id="nph12964-list-0001" list-type="bullet"> <list-item> <p>In anaerobiosis, the microalga <italic>Chlamydomonas reinhardtii</italic> is able to produce H<sub>2</sub> gas. Electrons mainly derive from mobilization of internal reserves or from water through biophotolysis. However, the exact mechanisms triggering this process are still unclear. Our hypothesis was that, once a proper redox state has been achieved, H<sub>2</sub> production is eventually observed.</p> </list-item> <list-item> <p>To avoid nutrient depletion, which would result in enhanced fermentative pathways, we aimed to induce long‐lasting H<sub>2</sub> production solely through a photosynthesis : respiration equilibrium. Thus, growing cells were incubated in Tris Acetate Phosphate (TAP) medium under low light and high chlorophyll content.</p> </list-item> <list-item> <p>After a 250‐h acclimation phase, a 350‐h H<sub>2</sub> production phase was observed. The light‐to‐H<sub>2</sub> conversion efficiency was comparable to that given in some reports operating under sulphur starvation. Electron sources were found to be water, through biophotolysis, and proteins, particularly through photofermentation. Nonetheless, a substantial contribution from acetate could not be ruled out. In addition, photosystem II (PSII) inhibition by 3‐(3, 4‐dichlorophenyl)‐1, 1‐dimethylurea (DCMU) showed that it actively contributed to maintaining a redox balance during cell acclimation.</p> </list-item> <list-item> <p>In appropriate conditions, PSII may represent the major source of reducing power to feed the H<sub>2</sub> evolution process, by inducing and maintaining an ideal excess of reducing power.</p> </list-item> </list> </p> </abstract>