Hydrogenases in green algae: do they save the algae's life and solve our energy problems?

Trends Plant Sci. 2002 Jun;7(6):246-50. doi: 10.1016/s1360-1385(02)02274-4.


Green algae are the only known eukaryotes with both oxygenic photosynthesis and a hydrogen metabolism. Recent physiological and genetic discoveries indicate a close connection between these metabolic pathways. The anaerobically inducible hydA genes of algae encode a special type of highly active [Fe]-hydrogenase. Electrons from reducing equivalents generated during fermentation enter the photosynthetic electron transport chain via the plastoquinone pool. They are transferred to the hydrogenase by photosystem I and ferredoxin. Thus, the [Fe]-hydrogenase is an electron 'valve' that enables the algae to survive under anaerobic conditions. During sulfur deprivation, illuminated algal cultures evolve large quantities of hydrogen gas, and this promises to be an alternative future energy source.

Publication types

  • Comparative Study

MeSH terms

  • Aerobiosis
  • Amino Acid Sequence
  • Anaerobiosis
  • Animals
  • Carbon Dioxide / metabolism
  • Chlamydomonas reinhardtii / enzymology
  • Chlamydomonas reinhardtii / genetics
  • Chlorophyta / enzymology*
  • Chlorophyta / genetics
  • Formates / metabolism
  • Humans
  • Hydrogen / metabolism
  • Hydrogenase / genetics*
  • Hydrogenase / metabolism
  • Iron-Sulfur Proteins / genetics*
  • Iron-Sulfur Proteins / metabolism
  • Light
  • Molecular Sequence Data
  • Photosynthesis / physiology
  • Photosynthetic Reaction Center Complex Proteins / metabolism
  • Photosystem I Protein Complex
  • Plants / enzymology
  • Plants / genetics
  • Sequence Homology, Amino Acid


  • Formates
  • Iron-Sulfur Proteins
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • formic acid
  • Carbon Dioxide
  • Hydrogen
  • iron hydrogenase
  • Hydrogenase