The Effect of Sulfur Re-Addition on H2 Photoproduction by Sulfur-Deprived Green Algae

Sergey Kosourov, Valeriya Makarova, Alexander S. Fedorov, Anatoly Tsygankov, Michael Seibert, Maria L. Ghirardi

Research output: Contribution to journalArticlepeer-review

68 Scopus Citations


Sulfur deprivation of algal cultures selectively and partially inactivates photosystem II (PSII)-catalyzed O2 evolution, induces anaerobiosis and hydrogenase expression, and results in sustained H2 photoproduction for several days. We show that re-addition of limiting amounts of sulfate (1-10 μM final concentration) to the cultures during the H 2-production phase temporarily reactivates PSII photochemical and O2-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-O2 sensors. However, concomitant H2 photoproduction is inhibited, possibly due to excessive intra-cellular levels of photosynthetically-evolved O2. 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.

Original languageAmerican English
Pages (from-to)295-305
Number of pages11
JournalPhotosynthesis Research
Issue number3
StatePublished - 2005

NREL Publication Number

  • NREL/JA-590-39363


  • Biohydrogen,Chlamydomonas reinhardtii
  • H photoproduction
  • Hydrogenase
  • Photosystem II activity
  • Sulfur deprivation
  • Sulfur re-addition


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