 Ferredoxin hydrogenase found in the green algae "Chlamydomonas reinhardtii" use supplied electrons from photosystem I to reduce protons into hydrogen gas.This electron supply transfer is possible through photosystem I interactions with photosynthetic electron transfer ferredoxin (PetF).The inter-conversion of protons and electrons with hydrogen gas allow organisms to modulate energy input and output, adjust organelle redox potential, and transduce chemical signals.