Editing Photosynthetic pigment (section)

==Bacteria==
Like plants, the [[cyanobacteria]] use water as an electron donor for photosynthesis and therefore liberate [[oxygen]]; they also use chlorophyll as a pigment. In addition, most cyanobacteria use [[phycobiliprotein]]s, water-soluble pigments which occur in the cytoplasm of the chloroplast, to capture light energy and pass it on to the chlorophylls. (Some cyanobacteria, the prochlorophytes, use chlorophyll b instead of phycobilin.) It is thought that the chloroplasts in plants and algae all evolved from cyanobacteria.

Several other groups of bacteria use the [[bacteriochlorophyll]] pigments (similar to the chlorophylls) for photosynthesis. Unlike the cyanobacteria, these bacteria do not produce oxygen; they typically use [[hydrogen sulfide]] rather than water as the electron donor.

Recently, a very different pigment has been found in some marine [[Gammaproteobacteria]]: [[proteorhodopsin]]. It is similar to and probably originated from bacteriorhodopsin (see below: under [[#Archaea]]).