CO2 + H2O = 6 [CH2O] + O2
Photosynthesis consists of two processes: light energy conversion to biochemical energy by a photochemical reaction, and CO2 reduction to organic compounds such as sugar phosphates, through the use of this biochemical energy by Calvin-cycle enzymes. Under certain conditions, however, instead of reducing CO2, a few groups of Microalgae and Cyanobacteria consume biochemical energy to produce molecular hydrogen. Hydrogenase and nitrogenase enzymes are both capable of hydrogen production.
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