The Cyanobacteria Anabaena

Cyanobacteria, as well as algae and green plants, use hydrogen atoms from water to reduce carbon dioxide to form carbohydrates, and during this process oxygen gas is given off (an oxygenic process). Cyanobacteria were the first organisms on earth to carry out oxygenic photosynthesis.

Anabaena, a cyanobacterium. Hans Paerl, author. Licensed for use, ASM MicrobeLibrary.