A1 Refereed original research article in a scientific journal
The effect of sulfur re-addition on H-2 photoproduction by sulfur-deprived green algae
Authors: Kosourov S, Makarova V, Fedorov AS, Tsygankov A, Seibert M, Ghirardi ML
Publisher: SPRINGER
Publication year: 2005
Journal: Photosynthesis Research
Journal name in source: PHOTOSYNTHESIS RESEARCH
Journal acronym: PHOTOSYNTH RES
Volume: 85
Issue: 3
First page : 295
Last page: 305
Number of pages: 11
ISSN: 0166-8595
DOI: https://doi.org/10.1007/s11120-005-5105-0
Abstract
Sulfur deprivation of algal cultures selectively and partially inactivates photosystem II (PSII)-catalyzed O-2 evolution, induces anaerobiosis and hydrogenase expression, and results in sustained H-2 photoproduction for several days. We show that re-addition of limiting amounts of sulfate (1-10 mu M final concentration) to the cultures during the H-2-production phase temporarily reactivates PSII photochemical and O-2-evolution activity and re-establishes higher rates of electron transport through the photosynthetic electron transport chain. The reactivation of PSII occurs by de novo D1 protein synthesis, but does not result in the re-establishment of aerobic conditions in the reactor, detectable by dissolved-O-2 sensors. However, concomitant H-2 photoproduction is inhibited, possibly due to excessive intra-cellular levels of photosynthetically-evolved O-2. The partial recovery of electron transport rates correlates with the re-oxidation of the plastoquinone (PQ) pool, as observed by pulse-amplitude modulated (PAM) and fluorescence-induction measurements. These results show that the presence of a more oxidized PQ pool releases some of the down-regulation of electron transport caused by the anaerobic conditions.
Sulfur deprivation of algal cultures selectively and partially inactivates photosystem II (PSII)-catalyzed O-2 evolution, induces anaerobiosis and hydrogenase expression, and results in sustained H-2 photoproduction for several days. We show that re-addition of limiting amounts of sulfate (1-10 mu M final concentration) to the cultures during the H-2-production phase temporarily reactivates PSII photochemical and O-2-evolution activity and re-establishes higher rates of electron transport through the photosynthetic electron transport chain. The reactivation of PSII occurs by de novo D1 protein synthesis, but does not result in the re-establishment of aerobic conditions in the reactor, detectable by dissolved-O-2 sensors. However, concomitant H-2 photoproduction is inhibited, possibly due to excessive intra-cellular levels of photosynthetically-evolved O-2. The partial recovery of electron transport rates correlates with the re-oxidation of the plastoquinone (PQ) pool, as observed by pulse-amplitude modulated (PAM) and fluorescence-induction measurements. These results show that the presence of a more oxidized PQ pool releases some of the down-regulation of electron transport caused by the anaerobic conditions.
UTU Research Portal