Photosynthesizing marine microorganisms can constitute a source of CO2 rather than a sink

Dan Tchernov, Miriam Hassidim, Assaf Vardi, Boaz Luz, Assaf Sukenik, Leonora Reinhold, Aaron Kaplan

Research output: Contribution to journalArticlepeer-review


The unexpected finding that certain major marine photosynthetic microorganisms can serve as a source of CO2 rather than a sink emerged during measurements of inorganic carbon fluxes associated with the CO2-concentrating mechanism. During steady-state photosynthesis, CO2 was evolved at sustained rates up to 5-fold that of photosynthesis; the steady-state external CO2 concentration reached was significantly higher than that at CO2-HCO3- equilibrium. The evolved CO2 originated from HCO3- taken up and intracellularly converted to CO2 in a light-dependent process. Our results bear implications for carbon cycling in the marine environment; the use of naturally-observed stable carbon isotope fractionations as paleobarometer and productivity probe; and for intracellular energy balance and pH regulation.

Original languageEnglish
Pages (from-to)949-953
Number of pages5
JournalCanadian Journal of Botany
Issue number6
StatePublished - Jun 1998
Externally publishedYes


  • CO evolution
  • Carbonic anhydrase
  • Cyanobacteria
  • Photosynthesis
  • Synechococcus

ASJC Scopus subject areas

  • Plant Science


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