Proteorhodopsin is related to the pigment in the retina that enables human vision in less intense light.

In 2000, American scientists discovered that many Marine bacteria contain a gene in their genome that encodes a new kind of light-harvesting pigment: proteorhodopsin.

Now, a decade later, the first direct evidence for the functioning of proteorhodopsin in native marine bacteria is presented, based on mutational analysis in a marine bacterium.